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Is there a fast and simple way to encode a JavaScript object into a string that I can pass via a GET request?
No jQuery, no other frameworks—just plain JavaScript :)
Like this:
serialize = function(obj) {
var str = [];
for (var p in obj)
if (obj.hasOwnProperty(p)) {
str.push(encodeURIComponent(p) + "=" + encodeURIComponent(obj[p]));
}
return str.join("&");
}
console.log(serialize({
foo: "hi there",
bar: "100%"
}));
// foo=hi%20there&bar=100%25
This one also converts recursive objects (using PHP "array" notation for the query string):
serialize = function(obj, prefix) {
var str = [],
p;
for (p in obj) {
if (obj.hasOwnProperty(p)) {
var k = prefix ? prefix + "[" + p + "]" : p,
v = obj[p];
str.push((v !== null && typeof v === "object") ?
serialize(v, k) :
encodeURIComponent(k) + "=" + encodeURIComponent(v));
}
}
return str.join("&");
}
console.log(serialize({
foo: "hi there",
bar: {
blah: 123,
quux: [1, 2, 3]
}
}));
// foo=hi%20there&bar%5Bblah%5D=123&bar%5Bquux%5D%5B0%5D=1&bar%5Bquux%5D%5B1%5D=2&bar%5Bquux%5D%5B2%5D=3
Just use URLSearchParams This works in all current browsers
new URLSearchParams(object).toString()
jQuery has a function for this, jQuery.param(). If you're already using it, you can use this:
Example:
var params = { width:1680, height:1050 };
var str = jQuery.param( params );
str now contains width=1680&height=1050.
I suggest using the URLSearchParams interface:
const searchParams = new URLSearchParams();
const params = {foo: "hi there", bar: "100%" };
Object.keys(params).forEach(key => searchParams.append(key, params[key]));
console.log(searchParams.toString())
Or by passing the search object into the constructor like this:
const params = {foo: "hi there", bar: "100%" };
const queryString = new URLSearchParams(params).toString();
console.log(queryString);
Use:
Object.keys(obj).reduce(function(a,k){a.push(k+'='+encodeURIComponent(obj[k]));return a},[]).join('&')
I like this one-liner, but I bet it would be a more popular answer if it matched the accepted answer semantically:
function serialize( obj ) {
let str = '?' + Object.keys(obj).reduce(function(a, k){
a.push(k + '=' + encodeURIComponent(obj[k]));
return a;
}, []).join('&');
return str;
}
Here's a one liner in ES6:
Object.keys(obj).map(k => `${encodeURIComponent(k)}=${encodeURIComponent(obj[k])}`).join('&');
With Node.js v6.6.3
const querystring = require('querystring')
const obj = {
foo: 'bar',
baz: 'tor'
}
let result = querystring.stringify(obj)
// foo=bar&baz=tor
Reference: Query string
Ruby on Rails and PHP style query builder
This method converts a JavaScript object into a URI query string. It also handles nested arrays and objects (in Ruby on Rails and PHP syntax):
function serializeQuery(params, prefix) {
const query = Object.keys(params).map((key) => {
const value = params[key];
if (params.constructor === Array)
key = `${prefix}[]`;
else if (params.constructor === Object)
key = (prefix ? `${prefix}[${key}]` : key);
if (typeof value === 'object')
return serializeQuery(value, key);
else
return `${key}=${encodeURIComponent(value)}`;
});
return [].concat.apply([], query).join('&');
}
Example Usage:
let params = {
a: 100,
b: 'has spaces',
c: [1, 2, 3],
d: { x: 9, y: 8}
}
serializeQuery(params)
// returns 'a=100&b=has%20spaces&c[]=1&c[]=2&c[]=3&d[x]=9&d[y]=8
A small amendment to the accepted solution by user187291:
serialize = function(obj) {
var str = [];
for(var p in obj){
if (obj.hasOwnProperty(p)) {
str.push(encodeURIComponent(p) + "=" + encodeURIComponent(obj[p]));
}
}
return str.join("&");
}
Checking for hasOwnProperty on the object makes JSLint and JSHint happy, and it prevents accidentally serializing methods of the object or other stuff if the object is anything but a simple dictionary. See the paragraph on for statements on Code Conventions for the JavaScript Programming Language.
Well, everyone seems to put his one-liner here so here goes mine:
const encoded = Object.entries(obj).map(([k, v]) => `${k}=${encodeURIComponent(v)}`).join("&");
If you need to send arbitrary objects, then GET is a bad idea since there are limits to the lengths of URLs that user agents and web servers will accepts. My suggestion would be to build up an array of name-value pairs to send and then build up a query string:
function QueryStringBuilder() {
var nameValues = [];
this.add = function(name, value) {
nameValues.push( {name: name, value: value} );
};
this.toQueryString = function() {
var segments = [], nameValue;
for (var i = 0, len = nameValues.length; i < len; i++) {
nameValue = nameValues[i];
segments[i] = encodeURIComponent(nameValue.name) + "=" + encodeURIComponent(nameValue.value);
}
return segments.join("&");
};
}
var qsb = new QueryStringBuilder();
qsb.add("veg", "cabbage");
qsb.add("vegCount", "5");
alert( qsb.toQueryString() );
A little bit look better
objectToQueryString(obj, prefix) {
return Object.keys(obj).map(objKey => {
if (obj.hasOwnProperty(objKey)) {
const key = prefix ? `${prefix}[${objKey}]` : objKey;
const value = obj[objKey];
return typeof value === "object" ?
this.objectToQueryString(value, key) :
`${encodeURIComponent(key)}=${encodeURIComponent(value)}`;
}
return null;
}).join("&");
}
This one skips null/undefined values
export function urlEncodeQueryParams(data) {
const params = Object.keys(data).map(key => data[key] ? `${encodeURIComponent(key)}=${encodeURIComponent(data[key])}` : '');
return params.filter(value => !!value).join('&');
}
Here's the CoffeeScript version of the accepted answer.
serialize = (obj, prefix) ->
str = []
for p, v of obj
k = if prefix then prefix + "[" + p + "]" else p
if typeof v == "object"
str.push(serialize(v, k))
else
str.push(encodeURIComponent(k) + "=" + encodeURIComponent(v))
str.join("&")
Here's a concise & recursive version with Object.entries. It handles arbitrarily nested arrays, but not nested objects. It also removes empty elements:
const format = (k,v) => v !== null ? `${k}=${encodeURIComponent(v)}` : ''
const to_qs = (obj) => {
return [].concat(...Object.entries(obj)
.map(([k,v]) => Array.isArray(v)
? v.map(arr => to_qs({[k]:arr}))
: format(k,v)))
.filter(x => x)
.join('&');
}
E.g.:
let json = {
a: [1, 2, 3],
b: [], // omit b
c: 1,
d: "test&encoding", // uriencode
e: [[4,5],[6,7]], // flatten this
f: null, // omit nulls
g: 0
};
let qs = to_qs(json)
=> "a=1&a=2&a=3&c=1&d=test%26encoding&e=4&e=5&e=6&e=7&g=0"
Use:
const toQueryString = obj => "?".concat(Object.keys(obj).map(e => `${encodeURIComponent(e)}=${encodeURIComponent(obj[e])}`).join("&"));
const data = {
offset: 5,
limit: 10
};
toQueryString(data); // => ?offset=5&limit=10
Or use a predefined feature
const data = {
offset: 5,
limit: 10
};
new URLSearchParams(data).toString(); // => ?offset=5&limit=10
Note
Both the above methods will set the value as null if not present.
If you want not to set the query parameter if value is null then use:
const toQueryString = obj => "?".concat(Object.keys(obj).map(e => obj[e] ? `${encodeURIComponent(e)}=${encodeURIComponent(obj[e])}` : null).filter(e => !!e).join("&"));
const data = {
offset: null,
limit: 10
};
toQueryString(data); // => "?limit=10" else with above methods "?offset=null&limit=10"
You can freely use any method.
In ES7 you can write this in one line:
const serialize = (obj) => (Object.entries(obj).map(i => [i[0], encodeURIComponent(i[1])].join('=')).join('&'))
I have a simpler solution that does not use any third-party library and is already apt to be used in any browser that has "Object.keys" (aka all modern browsers + edge + ie):
In ES5
function(a){
if( typeof(a) !== 'object' )
return '';
return `?${Object.keys(a).map(k=>`${k}=${a[k]}`).join('&')}`;
}
In ES3
function(a){
if( typeof(a) !== 'object' )
return '';
return '?' + Object.keys(a).map(function(k){ return k + '=' + a[k] }).join('&');
}
I made a comparison of JSON stringifiers and the results are as follows:
JSON: {"_id":"5973782bdb9a930533b05cb2","isActive":true,"balance":"$1,446.35","age":32,"name":"Logan Keller","email":"logankeller#artiq.com","phone":"+1 (952) 533-2258","friends":[{"id":0,"name":"Colon Salazar"},{"id":1,"name":"French Mcneil"},{"id":2,"name":"Carol Martin"}],"favoriteFruit":"banana"}
Rison: (_id:'5973782bdb9a930533b05cb2',age:32,balance:'$1,446.35',email:'logankeller#artiq.com',favoriteFruit:banana,friends:!((id:0,name:'Colon Salazar'),(id:1,name:'French Mcneil'),(id:2,name:'Carol Martin')),isActive:!t,name:'Logan Keller',phone:'+1 (952) 533-2258')
O-Rison: _id:'5973782bdb9a930533b05cb2',age:32,balance:'$1,446.35',email:'logankeller#artiq.com',favoriteFruit:banana,friends:!((id:0,name:'Colon Salazar'),(id:1,name:'French Mcneil'),(id:2,name:'Carol Martin')),isActive:!t,name:'Logan Keller',phone:'+1 (952) 533-2258'
JSURL: ~(_id~'5973782bdb9a930533b05cb2~isActive~true~balance~'!1*2c446.35~age~32~name~'Logan*20Keller~email~'logankeller*40artiq.com~phone~'*2b1*20*28952*29*20533-2258~friends~(~(id~0~name~'Colon*20Salazar)~(id~1~name~'French*20Mcneil)~(id~2~name~'Carol*20Martin))~favoriteFruit~'banana)
QS: _id=5973782bdb9a930533b05cb2&isActive=true&balance=$1,446.35&age=32&name=Logan Keller&email=logankeller#artiq.com&phone=+1 (952) 533-2258&friends[0][id]=0&friends[0][name]=Colon Salazar&friends[1][id]=1&friends[1][name]=French Mcneil&friends[2][id]=2&friends[2][name]=Carol Martin&favoriteFruit=banana
URLON: $_id=5973782bdb9a930533b05cb2&isActive:true&balance=$1,446.35&age:32&name=Logan%20Keller&email=logankeller#artiq.com&phone=+1%20(952)%20533-2258&friends#$id:0&name=Colon%20Salazar;&$id:1&name=French%20Mcneil;&$id:2&name=Carol%20Martin;;&favoriteFruit=banana
QS-JSON: isActive=true&balance=%241%2C446.35&age=32&name=Logan+Keller&email=logankeller%40artiq.com&phone=%2B1+(952)+533-2258&friends(0).id=0&friends(0).name=Colon+Salazar&friends(1).id=1&friends(1).name=French+Mcneil&friends(2).id=2&friends(2).name=Carol+Martin&favoriteFruit=banana
The shortest among them is URL Object Notation.
There another popular library, qs. You can add it by:
yarn add qs
And then use it like this:
import qs from 'qs'
const array = { a: { b: 'c' } }
const stringified = qs.stringify(array, { encode: false })
console.log(stringified) //-- outputs a[b]=c
ES6 solution for query string encoding of a JavaScript object
const params = {
a: 1,
b: 'query stringify',
c: null,
d: undefined,
f: '',
g: { foo: 1, bar: 2 },
h: ['Winterfell', 'Westeros', 'Braavos'],
i: { first: { second: { third: 3 }}}
}
static toQueryString(params = {}, prefix) {
const query = Object.keys(params).map((k) => {
let key = k;
const value = params[key];
if (!value && (value === null || value === undefined || isNaN(value))) {
value = '';
}
switch (params.constructor) {
case Array:
key = `${prefix}[]`;
break;
case Object:
key = (prefix ? `${prefix}[${key}]` : key);
break;
}
if (typeof value === 'object') {
return this.toQueryString(value, key); // for nested objects
}
return `${key}=${encodeURIComponent(value)}`;
});
return query.join('&');
}
toQueryString(params)
"a=1&b=query%20stringify&c=&d=&f=&g[foo]=1&g[bar]=2&h[]=Winterfell&h[]=Westeros&h[]=Braavos&i[first][second][third]=3"
A single line to convert an object into a query string in case somebody needs it again:
let Objs = { a: 'obejct-a', b: 'object-b' }
Object.keys(objs).map(key => key + '=' + objs[key]).join('&')
// The result will be a=object-a&b=object-b
This is an addition for the accepted solution. This works with objects and array of objects:
parseJsonAsQueryString = function (obj, prefix, objName) {
var str = [];
for (var p in obj) {
if (obj.hasOwnProperty(p)) {
var v = obj[p];
if (typeof v == "object") {
var k = (objName ? objName + '.' : '') + (prefix ? prefix + "[" + p + "]" : p);
str.push(parseJsonAsQueryString(v, k));
} else {
var k = (objName ? objName + '.' : '') + (prefix ? prefix + '.' + p : p);
str.push(encodeURIComponent(k) + "=" + encodeURIComponent(v));
//str.push(k + "=" + v);
}
}
}
return str.join("&");
}
Also I have added objName if you're using object parameters, like in ASP.NET MVC action methods.
If you want to convert a nested object recursively and the object may or may not contain arrays (and the arrays may contain objects or arrays, etc), then the solution gets a little more complex. This is my attempt.
I've also added some options to choose if you want to record for each object member at what depth in the main object it sits, and to choose if you want to add a label to the members that come from converted arrays.
Ideally you should test if the thing parameter really receives an object or array.
function thingToString(thing,maxDepth,recordLevel,markArrays){
//thing: object or array to be recursively serialized
//maxDepth (int or false):
// (int) how deep to go with converting objects/arrays within objs/arrays
// (false) no limit to recursive objects/arrays within objects/arrays
//recordLevel (boolean):
// true - insert "(level 1)" before transcript of members at level one (etc)
// false - just
//markArrays (boolean):
// insert text to indicate any members that came from arrays
var result = "";
if (maxDepth !== false && typeof maxDepth != 'number') {maxDepth = 3;}
var runningDepth = 0;//Keeps track how deep we're into recursion
//First prepare the function, so that it can call itself recursively
function serializeAnything(thing){
//Set path-finder values
runningDepth += 1;
if(recordLevel){result += "(level " + runningDepth + ")";}
//First convert any arrays to object so they can be processed
if (thing instanceof Array){
var realObj = {};var key;
if (markArrays) {realObj['type'] = "converted array";}
for (var i = 0;i < thing.length;i++){
if (markArrays) {key = "a" + i;} else {key = i;}
realObj[key] = thing[i];
}
thing = realObj;
console.log('converted one array to ' + typeof realObj);
console.log(thing);
}
//Then deal with it
for (var member in thing){
if (typeof thing[member] == 'object' && runningDepth < maxDepth){
serializeAnything(thing[member]);
//When a sub-object/array is serialized, it will add one to
//running depth. But when we continue to this object/array's
//next sibling, the level must go back up by one
runningDepth -= 1;
} else if (maxDepth !== false && runningDepth >= maxDepth) {
console.log('Reached bottom');
} else
if (
typeof thing[member] == "string" ||
typeof thing[member] == 'boolean' ||
typeof thing[member] == 'number'
){
result += "(" + member + ": " + thing[member] + ") ";
} else {
result += "(" + member + ": [" + typeof thing[member] + " not supported]) ";
}
}
}
//Actually kick off the serialization
serializeAnything(thing);
return result;
}
This is a solution that will work for .NET backends out of the box. I have taken the primary answer of this thread and updated it to fit our .NET needs.
function objectToQuerystring(params) {
var result = '';
function convertJsonToQueryString(data, progress, name) {
name = name || '';
progress = progress || '';
if (typeof data === 'object') {
Object.keys(data).forEach(function (key) {
var value = data[key];
if (name == '') {
convertJsonToQueryString(value, progress, key);
} else {
if (isNaN(parseInt(key))) {
convertJsonToQueryString(value, progress, name + '.' + key);
} else {
convertJsonToQueryString(value, progress, name + '[' + key+ ']');
}
}
})
} else {
result = result ? result.concat('&') : result.concat('?');
result = result.concat(`${name}=${data}`);
}
}
convertJsonToQueryString(params);
return result;
}
To do it in a better way.
It can handle recursive objects or arrays in the standard query form, like a=val&b[0]=val&b[1]=val&c=val&d[some key]=val. Here's the final function.
Logic, Functionality
const objectToQueryString = (initialObj) => {
const reducer = (obj, parentPrefix = null) => (prev, key) => {
const val = obj[key];
key = encodeURIComponent(key);
const prefix = parentPrefix ? `${parentPrefix}[${key}]` : key;
if (val == null || typeof val === 'function') {
prev.push(`${prefix}=`);
return prev;
}
if (['number', 'boolean', 'string'].includes(typeof val)) {
prev.push(`${prefix}=${encodeURIComponent(val)}`);
return prev;
}
prev.push(Object.keys(val).reduce(reducer(val, prefix), []).join('&'));
return prev;
};
return Object.keys(initialObj).reduce(reducer(initialObj), []).join('&');
};
Example
const testCase1 = {
name: 'Full Name',
age: 30
}
const testCase2 = {
name: 'Full Name',
age: 30,
children: [
{name: 'Child foo'},
{name: 'Foo again'}
],
wife: {
name: 'Very Difficult to say here'
}
}
console.log(objectToQueryString(testCase1));
console.log(objectToQueryString(testCase2));
Live Test
Expand the snippet below to verify the result in your browser -
const objectToQueryString = (initialObj) => {
const reducer = (obj, parentPrefix = null) => (prev, key) => {
const val = obj[key];
key = encodeURIComponent(key);
const prefix = parentPrefix ? `${parentPrefix}[${key}]` : key;
if (val == null || typeof val === 'function') {
prev.push(`${prefix}=`);
return prev;
}
if (['number', 'boolean', 'string'].includes(typeof val)) {
prev.push(`${prefix}=${encodeURIComponent(val)}`);
return prev;
}
prev.push(Object.keys(val).reduce(reducer(val, prefix), []).join('&'));
return prev;
};
return Object.keys(initialObj).reduce(reducer(initialObj), []).join('&');
};
const testCase1 = {
name: 'Full Name',
age: 30
}
const testCase2 = {
name: 'Full Name',
age: 30,
children: [
{name: 'Child foo'},
{name: 'Foo again'}
],
wife: {
name: 'Very Difficult to say here'
}
}
console.log(objectToQueryString(testCase1));
console.log(objectToQueryString(testCase2));
Things to consider.
It skips values for functions, null, and undefined
It skips keys and values for empty objects and arrays.
It doesn't handle Number or String objects made with new Number(1) or new String('my string') because no one should ever do that
ok, it's a older post but i'm facing this problem and i have found my personal solution.. maybe can help someone else..
function objToQueryString(obj){
var k = Object.keys(obj);
var s = "";
for(var i=0;i<k.length;i++) {
s += k[i] + "=" + encodeURIComponent(obj[k[i]]);
if (i != k.length -1) s += "&";
}
return s;
};
URLSearchParams looks good, but it didn't work for nested objects.
Try to use
encodeURIComponent(JSON.stringify(object))
The previous answers do not work if you have a lot of nested objects.
Instead you can pick the function parameter from jquery-param/jquery-param.js. It worked very well for me!
var param = function (a) {
var s = [], rbracket = /\[\]$/,
isArray = function (obj) {
return Object.prototype.toString.call(obj) === '[object Array]';
}, add = function (k, v) {
v = typeof v === 'function' ? v() : v === null ? '' : v === undefined ? '' : v;
s[s.length] = encodeURIComponent(k) + '=' + encodeURIComponent(v);
}, buildParams = function (prefix, obj) {
var i, len, key;
if (prefix) {
if (isArray(obj)) {
for (i = 0, len = obj.length; i < len; i++) {
if (rbracket.test(prefix)) {
add(prefix, obj[i]);
} else {
buildParams(prefix + '[' + (typeof obj[i] === 'object' ? i : '') + ']', obj[i]);
}
}
} else if (obj && String(obj) === '[object Object]') {
for (key in obj) {
buildParams(prefix + '[' + key + ']', obj[key]);
}
} else {
add(prefix, obj);
}
} else if (isArray(obj)) {
for (i = 0, len = obj.length; i < len; i++) {
add(obj[i].name, obj[i].value);
}
} else {
for (key in obj) {
buildParams(key, obj[key]);
}
}
return s;
};
return buildParams('', a).join('&').replace(/%20/g, '+');
};
After going through some top answers here, I have wrote another implementation that tackles some edge cases as well
function serialize(params, prefix) {
return Object.entries(params).reduce((acc, [key, value]) => {
// remove whitespace from both sides of the key before encoding
key = encodeURIComponent(key.trim());
if (params.constructor === Array ) {
key = `${prefix}[]`;
} else if (params.constructor === Object) {
key = (prefix ? `${prefix}[${key}]` : key);
}
/**
* - undefined and NaN values will be skipped automatically
* - value will be empty string for functions and null
* - nested arrays will be flattened
*/
if (value === null || typeof value === 'function') {
acc.push(`${key}=`);
} else if (typeof value === 'object') {
acc = acc.concat(serialize(value, key));
} else if(['number', 'boolean', 'string'].includes(typeof value) && value === value) { // self-check to avoid NaN
acc.push(`${key}=${encodeURIComponent(value)}`);
}
return acc;
}, []);
}
function objectToQueryString(queryParameters) {
return queryParameters ? serialize(queryParameters).join('&'): '';
}
let x = objectToQueryString({
foo: 'hello world',
bar: {
blah: 123,
list: [1, 2, 3],
'nested array': [[4,5],[6,7]] // will be flattened
},
page: 1,
limit: undefined, // field will be ignored
check: false,
max: NaN, // field will be ignored
prop: null,
' key value': 'with spaces' // space in key will be trimmed out
});
console.log(x); // foo=hello%20world&bar[blah]=123&bar[list][]=1&bar[list][]=2&bar[list][]=3&bar[nested%20array][][]=4&bar[nested%20array][][]=5&bar[nested%20array][][]=6&bar[nested%20array][][]=7&page=1&check=false&prop=&key%20value=with%20spaces
Here is my requirement. I was able to achieve to some level in java but we need to move it to typescript (client side).
Note: The below input is for example purpose and may vary dynamically.
Input
var input = ["a.name", "a.type", "b.city.name" , "b.city.zip", "b.desc","c"];
We need to create an utility function that takes above input and returns output as below.
Output:
Should be string not an object or anything else.
"{ a { name, type }, b { city {name, zip } , desc }, c }"
any help is much appreciated.
I don't see that typescript plays any role in your question, but here's a solution for constructing the string you requested. I first turn the array into an object with those properties, then have a function which can turn an object into a string formatted like you have
const input = ["a.name", "a.type", "b.city.name" , "b.city.zip", "b.desc","c"];
const arrayToObject = (arr) => {
return arr.reduce((result, val) => {
const path = val.split('.');
let obj = result;
path.forEach(key => {
obj[key] = obj[key] || {};
obj = obj[key];
});
return result;
}, {});
}
const objectToString = (obj, name = '') => {
const keys = Object.keys(obj);
if (keys.length === 0) {
return name;
}
return `${name} { ${keys.map(k => objectToString(obj[k], k)).join(', ')} }`;
}
const arrayToString = arr => objectToString(arrayToObject(arr));
console.log(arrayToString(input));
Here's another variation. Trick is to parse the strings recursively and store the intermediate results in an Object.
function dotStringToObject(remainder, parent) {
if (remainder.indexOf('.') === -1) {
return parent[remainder] = true
} else {
var subs = remainder.split('.');
dotStringToObject(subs.slice(1).join('.'), (parent[subs[0]] || (parent[subs[0]] = {})))
}
}
var output = {};
["a.name", "a.type", "b.city.name" , "b.city.zip", "b.desc","c"].forEach(function(entry) {
dotStringToObject(entry, output)
});
var res = JSON.stringify(output).replace(/\"/gi, ' ').replace(/\:|true/gi, '').replace(/\s,\s/gi, ', ');
console.log(res)
// Prints: { a { name, type }, b { city { name, zip }, desc }, c }
You could do something like this:
var input = ["a.name", "a.type", "b.city.name" , "b.city.zip", "b.desc","c"];
var output = {};
for(var i =0; i < input.length; i+=2){
output[String.fromCharCode(i+97)] = {};
output[String.fromCharCode(i+97)].name = input[i];
output[String.fromCharCode(i+97)].type = input[i+1];
}
console.log(JSON.stringify(output));
I have a requirement where I have an object like obj={ 'a.b.c' : d }
and I would like it to get converted to {a:{b:{c:d}}}
Is there any way I can achieve this in JavaScript?
Here's a solution (EDITED: code is more complex than before but it gives the result you want, let me know if something doesn't work):
var obj = {
'a.b.c': 22,
'a.b.d.e': 42
}
var newObj = {};
for (var key in obj) {
if (obj.hasOwnProperty(key)) {
var keyList = key.split('.');
newObj = generateNewObject(keyList, keyList.length - 1, newObj, obj[key]);
}
}
console.log(newObj);
function generateNewObject(keys, index, existingObj, value) {
if (index < 0) {
return value;
}
var lastKey = keys[index--];
var existingProperty = getProperty(existingObj, lastKey);
if (existingProperty != null && !objectsAreEqual(existingProperty, value)) {
var valueKey = keys[index + 2];
existingProperty[lastKey][valueKey] = value[valueKey];
value = existingProperty;
} else {
var subObj = {};
subObj[lastKey] = value;
value = subObj;
}
return generateNewObject(keys, index, existingObj, value);
}
function objectsAreEqual(obj1, obj2) {
for (var key in obj1) {
if (obj1.hasOwnProperty(key)) {
var prop = getProperty(obj2, key);
if (prop == null) {
return false;
}
}
}
return true;
}
function getProperty(obj, keyDesired) {
for (var key in obj) {
if (obj.hasOwnProperty(key)) {
if (key === keyDesired) {
return obj;
} else {
var prop = getProperty(obj[key], keyDesired);
if (prop != null) {
return prop;
}
}
}
}
return null;
}
I don't know why you would have an object named that way, but this code will do the trick for each key in an object. This will not work correctly on nested objects such as {'a' : { 'b' { 'c' : {{'d' : 'e'}}}}}. You would have to repeat the for-loop part each time the value is a JavaScript object.
EDIT
I modified the code so it recognizes when two properties are the same such as the example { 'a.b.c' : 22 }, 'a.b.c.d.e' : 42. Sorry if it is hard to go through, but basically the generateNewObject method is the real meat of it. The two functions below it are just helper methods.
Array.reduce mostly is a good choice when it comes to handling/transforming of more complex data structures. An approach that solves the given problem generically whilst taking edge cases into account then might look similar to the next provided example ...
var
d = 'd',
q = 'q',
obj = {
'i.k.l.m.n.o.p' : q,
'a.b.c' : d,
'foo' : 'bar',
'' : 'empty'
};
function parseIntoNestedTypes(type) {
return Object.keys(type).reduce(function (collector, integralKey) {
var
nestedType = collector.target,
fragmentedKeyList = integralKey.split('.'),
nestedTypeRootKey = fragmentedKeyList.shift(),
nestedTypeEndValue = collector.source[integralKey];
if (fragmentedKeyList.length === 0) {
nestedType[nestedTypeRootKey] = nestedTypeEndValue;
} else {
nestedType[nestedTypeRootKey] = fragmentedKeyList.reduce(function (collector, key, idx, list) {
var
partialType = collector.partialType || collector.type;
if (idx < (list.length - 1)) {
partialType[key] = {};
} else {
partialType[key] = collector.value;
}
collector.partialType = partialType[key];
return collector;
}, {
value : nestedTypeEndValue,
type : {}
}).type;
}
return collector;
}, {
source: type,
target: {}
}).target;
}
console.log('parseIntoNestedTypes :: type', JSON.stringify(obj));
console.log('parseIntoNestedTypes :: nestedType', JSON.stringify(parseIntoNestedTypes(obj)));
console.log('parseIntoNestedTypes :: type, nestedType : ', obj, parseIntoNestedTypes(obj));
JSFiddle: http://jsfiddle.net/3WdzL/1/
I need to convert locale JS object files to flattened versions and back again:
Orig locale object:
var localeObj = {
toolbar: {
link: {
back: 'Back',
menu: 'Menu',
},
flatTest: 'something'
},
countries: [
["AF", "Afghanistan"],
["AX", "Åland Islands"],
['nested', [1, 2, 3, 4]],
["AL", "Albania"]
]
};
Using the following function:
function flattenObj(obj) {
var flattenedObj = {};
var walk = function(obj, stringMap) {
for(k in obj) {
var computedKey = stringMap + (stringMap ? '.' + k : k);
if(typeof obj[k] !== 'object') {
flattenedObj[computedKey] = obj[k];
} else {
walk(obj[k], computedKey);
}
}
};
walk(obj, '');
return flattenedObj;
}
Would produce a flattened object:
{
toolbar.link.back: Back
toolbar.link.menu: Menu
toolbar.flatTest: something
countries.0.0: AF
countries.0.1: Afghanistan
countries.1.0: AX
countries.1.1: Åland Islands
countries.2.0: nested
countries.2.1.0: 1
countries.2.1.1: 2
countries.2.1.2: 3
countries.2.1.3: 4
countries.3.0: AL
countries.3.1: Albania
}
Converting back with the following func works fine for objects:
function deepenObj(obj) {
var deepenedObj = {}, tmp, parts, part;
for (var k in obj) {
tmp = deepenedObj;
parts = k.split('.');
var computedKey = parts.pop();
while (parts.length) {
part = parts.shift();
tmp = tmp[part] = tmp[part] || {};
}
tmp[computedKey] = obj[k];
}
return deepenedObj;
}
But produces a structure like this for the arrays:
region: {
country: {
0: {
0: 'AF',
1: 'Afghanistan'
},
...
2: {
0: 'nested',
1: {
0: 1,
1: 2,
3: 4,
4: 5
}
}
}
}
Obviously this isn't the desired results for the arrays and I haven't been able to come up with a safe, elegant or even working solution yet. PS I am happy to save the arrays to strings differently if it makes converting back easier. Thanks!
You should either keep track if an object is actually an array:
var walk = function(obj, stringMap) {
if (Array.isArray(obj) {
for (var k = 0; k < obj.length; k++)
var computedKey = stringMap ? stringMap + ',' + k : k;
} else {
for (var k in obj) {
var computedKey = stringMap ? stringMap + '.' + k : k;
...
Then, when deepening:
for (var k in obj) {
tmp = deepenedObj;
parts = ["."].concat(k.split(/([\.,])/));
var computedKey = parts.pop(), sign;
while (parts.length) {
sign = parts.shift();
part = !parts.length ? computedKey : parts.shift();
tmp = tmp[part] = tmp[part] || (sign === "," ? [] : {});
}
tmp[computedKey] = obj[k];
}
Note that Array.isArray could be undefined. You can use obj instanceof Array instead.
This solution works if localeObj is an object literal and not an array, because the first point/comma isn't saved in the computed key. You can modify the function if you need to.
The trick here is to use an unusual behaviour of split that pushes captured groups in the splitted array when used with regular expressions, so before every key part there's the proper separator.
Use JSON.stringify() and JSON.parse():
var flattenedObj = JSON.stringify(localeObj);
vat deepenedObj = JSON.parse(flattenedObj);
Demo
I want to create a hash table with Object keys that are not converted into String.
Some thing like this:
var object1 = new Object();
var object2 = new Object();
var myHash = new HashTable();
myHash.put(object1, "value1");
myHash.put(object2, "value2");
alert(myHash.get(object1), myHash.get(object2)); // I wish that it will print value1 value2
EDIT: See my answer for full solution
Here is a simple Map implementation that will work with any type of key, including object references, and it will not mutate the key in any way:
function Map() {
var keys = [], values = [];
return {
put: function (key, value) {
var index = keys.indexOf(key);
if(index == -1) {
keys.push(key);
values.push(value);
}
else {
values[index] = value;
}
},
get: function (key) {
return values[keys.indexOf(key)];
}
};
}
While this yields the same functionality as a hash table, it's not actually implemented using a hash function since it iterates over arrays and has a worst case performance of O(n). However, for the vast majority of sensible use cases this shouldn't be a problem at all. The indexOf function is implemented by the JavaScript engine and is highly optimized.
Here is a proposal:
function HashTable() {
this.hashes = {};
}
HashTable.prototype = {
constructor: HashTable,
put: function( key, value ) {
this.hashes[ JSON.stringify( key ) ] = value;
},
get: function( key ) {
return this.hashes[ JSON.stringify( key ) ];
}
};
The API is exactly as shown in your question.
You can't play with the reference in js however (so two empty objects will look like the same to the hashtable), because you have no way to get it. See this answer for more details: How to get javascript object references or reference count?
Jsfiddle demo: http://jsfiddle.net/HKz3e/
However, for the unique side of things, you could play with the original objects, like in this way:
function HashTable() {
this.hashes = {},
this.id = 0;
}
HashTable.prototype = {
constructor: HashTable,
put: function( obj, value ) {
obj.id = this.id;
this.hashes[ this.id ] = value;
this.id++;
},
get: function( obj ) {
return this.hashes[ obj.id ];
}
};
Jsfiddle demo: http://jsfiddle.net/HKz3e/2/
This means that your objects need to have a property named id that you won't use elsewhere. If you want to have this property as non-enumerable, I suggest you take a look at defineProperty (it's not cross-browser however, even with ES5-Shim, it doesn't work in IE7).
It also means you are limited on the number of items you can store in this hashtable. Limited to 253, that is.
And now, the "it's not going to work anywhere" solution: use ES6 WeakMaps. They are done exactly for this purpose: having objects as keys. I suggest you read MDN for more information: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/WeakMap
It slightly differs from your API though (it's set and not put):
var myMap = new WeakMap(),
object1 = {},
object2 = {};
myMap.set( object1, 'value1' );
myMap.set( object2, 'value2' );
console.log( myMap.get( object1 ) ); // "value1"
console.log( myMap.get( object2 ) ); // "value2"
Jsfiddle demo with a weakmap shim: http://jsfiddle.net/Ralt/HKz3e/9/
However, weakmaps are implemented in FF and Chrome (only if you enable the "Experimental javascript features" flag in chrome however). There are shims available, like this one: https://gist.github.com/1269991. Use at your own risk.
You can also use Maps, they may more suit your needs, since you also need to store primitive values (strings) as keys. Doc, Shim.
I took #Florian Margaine's suggestion to higher level and came up with this:
function HashTable(){
var hash = new Object();
this.put = function(key, value){
if(typeof key === "string"){
hash[key] = value;
}
else{
if(key._hashtableUniqueId == undefined){
key._hashtableUniqueId = UniqueId.prototype.generateId();
}
hash[key._hashtableUniqueId] = value;
}
};
this.get = function(key){
if(typeof key === "string"){
return hash[key];
}
if(key._hashtableUniqueId == undefined){
return undefined;
}
return hash[key._hashtableUniqueId];
};
}
function UniqueId(){
}
UniqueId.prototype._id = 0;
UniqueId.prototype.generateId = function(){
return (++UniqueId.prototype._id).toString();
};
Usage
var map = new HashTable();
var object1 = new Object();
map.put(object1, "Cocakola");
alert(map.get(object1)); // Cocakola
//Overriding
map.put(object1, "Cocakola 2");
alert(map.get(object1)); // Cocakola 2
// String key is used as String
map.put("myKey", "MyValue");
alert(map.get("myKey")); // MyValue
alert(map.get("my".concat("Key"))); // MyValue
// Invalid keys
alert(map.get("unknownKey")); // undefined
alert(map.get(new Object())); // undefined
Here is a proposal, combining #Florian's solution with #Laurent's.
function HashTable() {
this.hashes = [];
}
HashTable.prototype = {
constructor: HashTable,
put: function( key, value ) {
this.hashes.push({
key: key,
value: value
});
},
get: function( key ) {
for( var i = 0; i < this.hashes.length; i++ ){
if(this.hashes[i].key == key){
return this.hashes[i].value;
}
}
}
};
It wont change your object in any way and it doesn't rely on JSON.stringify.
I know that I am a year late, but for all others who stumble upon this thread, I've written the ordered object stringify to JSON, that solves the above noted dilemma: http://stamat.wordpress.com/javascript-object-ordered-property-stringify/
Also I was playing with custom hash table implementations which is also related to the topic: http://stamat.wordpress.com/javascript-quickly-find-very-large-objects-in-a-large-array/
//SORT WITH STRINGIFICATION
var orderedStringify = function(o, fn) {
var props = [];
var res = '{';
for(var i in o) {
props.push(i);
}
props = props.sort(fn);
for(var i = 0; i < props.length; i++) {
var val = o[props[i]];
var type = types[whatis(val)];
if(type === 3) {
val = orderedStringify(val, fn);
} else if(type === 2) {
val = arrayStringify(val, fn);
} else if(type === 1) {
val = '"'+val+'"';
}
if(type !== 4)
res += '"'+props[i]+'":'+ val+',';
}
return res.substring(res, res.lastIndexOf(','))+'}';
};
//orderedStringify for array containing objects
var arrayStringify = function(a, fn) {
var res = '[';
for(var i = 0; i < a.length; i++) {
var val = a[i];
var type = types[whatis(val)];
if(type === 3) {
val = orderedStringify(val, fn);
} else if(type === 2) {
val = arrayStringify(val);
} else if(type === 1) {
val = '"'+val+'"';
}
if(type !== 4)
res += ''+ val+',';
}
return res.substring(res, res.lastIndexOf(','))+']';
}
Based on Peters answer, but with proper class design (not abusing closures), so the values are debuggable. Renamed from Map to ObjectMap, because Map is a builtin function. Also added the exists method:
ObjectMap = function() {
this.keys = [];
this.values = [];
}
ObjectMap.prototype.set = function(key, value) {
var index = this.keys.indexOf(key);
if (index == -1) {
this.keys.push(key);
this.values.push(value);
} else {
this.values[index] = value;
}
}
ObjectMap.prototype.get = function(key) {
return this.values[ this.keys.indexOf(key) ];
}
ObjectMap.prototype.exists = function(key) {
return this.keys.indexOf(key) != -1;
}
/*
TestObject = function() {}
testA = new TestObject()
testB = new TestObject()
om = new ObjectMap()
om.set(testA, true)
om.get(testB)
om.exists(testB)
om.exists(testA)
om.exists(testB)
*/
When you say you don't want your Object keys converted into Strings, I'm going to assume it's because you just don't want the entire code contents of your Objects being used as keys. This, of course, makes perfect sense.
While there is no "hash table" in Javascript per-se, you can accomplish what you're looking for by simply overriding your Object's prototype.toString and returning a valid key value that will be unique to each instance. One way to do this is with Symbol():
function Obj () {
this.symbol = Symbol() // Guaranteed to be unique to each instance
}
Obj.prototype.toString = function () {
return this.symbol // Return the unique Symbol, instead of Obj's stringified code
}
let a = new Obj()
let b = new Obj()
let table = {}
table[a] = 'A'
table[b] = 'B'
console.log(table) // {Symbol(): 'A', Symbol(): 'B'}
console.log(table[a]) // A
console.log(table[b]) // B
Using JSON.stringify() is completely awkward to me, and gives the client no real control over how their keys are uniquely identified. The objects that are used as keys should have a hashing function, but my guess is that in most cases overriding the toString() method, so that they will return unique strings, will work fine:
var myMap = {};
var myKey = { toString: function(){ return '12345' }};
var myValue = 6;
// same as myMap['12345']
myMap[myKey] = myValue;
Obviously, toString() should do something meaningful with the object's properties to create a unique string. If you want to enforce that your keys are valid, you can create a wrapper and in the get() and put() methods, add a check like:
if(!key.hasOwnProperty('toString')){
throw(new Error('keys must override toString()'));
}
But if you are going to go thru that much work, you may as well use something other than toString(); something that makes your intent more clear.
So a very simple proposal would be:
function HashTable() {
this.hashes = {};
}
HashTable.prototype = {
constructor: HashTable,
put: function( key, value ) {
// check that the key is meaningful,
// also will cause an error if primitive type
if( !key.hasOwnProperty( 'hashString' ) ){
throw( new Error( 'keys must implement hashString()' ) );
}
// use .hashString() because it makes the intent of the code clear
this.hashes[ key.hashString() ] = value;
},
get: function( key ) {
// check that the key is meaningful,
// also will cause an error if primitive type
if( !key.hasOwnProperty( 'hashString' ) ){
throw( new Error( 'keys must implement hashString()' ) );
}
// use .hashString() because it make the intent of the code clear
return this.hashes[ key.hashString() ];
}
};
Inspired by #florian, here's a way where the id doesn't need JSON.stringify:
'use strict';
module.exports = HashTable;
function HashTable () {
this.index = [];
this.table = [];
}
HashTable.prototype = {
constructor: HashTable,
set: function (id, key, value) {
var index = this.index.indexOf(id);
if (index === -1) {
index = this.index.length;
this.index.push(id);
this.table[index] = {};
}
this.table[index][key] = value;
},
get: function (id, key) {
var index = this.index.indexOf(id);
if (index === -1) {
return undefined;
}
return this.table[index][key];
}
};
I took #Ilya_Gazman solution and improved it by setting '_hashtableUniqueId' as a not enumerable property (it won't appear in JSON requests neither will be listed in for loops). Also removed UniqueId object, since it is enough using only HastTable function closure. For usage details please see Ilya_Gazman post
function HashTable() {
var hash = new Object();
return {
put: function (key, value) {
if(!HashTable.uid){
HashTable.uid = 0;
}
if (typeof key === "string") {
hash[key] = value;
} else {
if (key._hashtableUniqueId === undefined) {
Object.defineProperty(key, '_hashtableUniqueId', {
enumerable: false,
value: HashTable.uid++
});
}
hash[key._hashtableUniqueId] = value;
}
},
get: function (key) {
if (typeof key === "string") {
return hash[key];
}
if (key._hashtableUniqueId === undefined) {
return undefined;
}
return hash[key._hashtableUniqueId];
}
};
}
The best solution is to use WeakMap when you can (i.e. when you target browsers supporting it)
Otherwise you can use the following workaround (Typescript written and collision safe):
// Run this in the beginning of your app (or put it into a file you just import)
(enableObjectID)();
const uniqueId: symbol = Symbol('The unique id of an object');
function enableObjectID(): void {
if (typeof Object['id'] !== 'undefined') {
return;
}
let id: number = 0;
Object['id'] = (object: any) => {
const hasUniqueId: boolean = !!object[uniqueId];
if (!hasUniqueId) {
object[uniqueId] = ++id;
}
return object[uniqueId];
};
}
Then you can simply get a unique number for any object in your code (like if would have been for pointer address)
let objectA = {};
let objectB = {};
let dico = {};
dico[(<any>Object).id(objectA)] = "value1";
// or
dico[Object['id'](objectA);] = "value1";
// If you are not using typescript you don't need the casting
dico[Object.id(objectA)] = "value1"
I know I'm late, but here's a simple HashMap implementation:
Function.prototype.toJSON = Function.prototype.toString;
//taken from https://stackoverflow.com/questions/1249531/how-to-get-a-javascript-objects-class
function getNativeClass(obj) {
if (typeof obj === "undefined") return "undefined";
if (obj === null) return "null";
return Object.prototype.toString.call(obj).match(/^\[object\s(.*)\]$/)[1];
}
function globals() {
if (typeof global === "object") //node
return global;
return this;
}
function lookup(x) {
return globals()[x];
}
function getAnyClass(obj) {
if (typeof obj === "undefined") return "undefined";
if (obj === null) return "null";
return obj.constructor.name;
}
//taken from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Errors/Cyclic_object_value#examples
var getCircularReplacer = () => {
const seen = new WeakSet();
return (key, value) => {
if (typeof value === "object" && value !== null) {
if (seen.has(value)) {
return "[Circular]";
}
seen.add(value);
}
return value;
};
};
function encode(x) {
if (typeof x === "object" && x !== null) {
var y = myClone(x);
x = Object.getPrototypeOf(x);
for (var i = 0; i < Object.getOwnPropertyNames(y).length; i++) { //Make enumerable
x[Object.getOwnPropertyNames(y)[i]] = y[Object.getOwnPropertyNames(y)[i]];
}
}
return getAnyClass(x) + " " + JSON.stringify(x, getCircularReplacer());
}
function decode(x) {
var a = x.split(" ").slice(1).join(" "); //OBJECT
if (typeof lookup(x.split(" ")[0])) {
return new (lookup(x.split(" ")[0]))(JSON.parse(a))
} else {
return JSON.parse(a);
}
}
//taken from https://github.com/feross/fromentries/blob/master/index.js
/*! fromentries. MIT License. Feross Aboukhadijeh <https://feross.org/opensource> */
function fromEntries(iterable) {
return [...iterable].reduce((obj, [key, val]) => {
obj[key] = val
return obj
}, {})
}
var toEnumerable = (obj) => {
return fromEntries(
Object.getOwnPropertyNames(obj).map(prop => [prop, obj[prop]])
);
};
//taken from https://stackoverflow.com/questions/41474986/how-to-clone-a-javascript-es6-class-instance
function myClone(instanceOfBlah) {
if (typeof instanceOfBlah !== "object" || !instanceOfBlah) { return instanceOfBlah; }
const clone = Object.assign({}, toEnumerable(instanceOfBlah));
const Blah = instanceOfBlah.constructor;
Object.setPrototypeOf(clone, Blah.prototype);
return clone;
}
function HashMap(a) {
if (typeof a === "undefined") {
a = [];
}
a = Array.from(a);
a = a.map((e) => [encode(e[0]), e[1]]);
this.a = a;
}
HashMap.from = function (a) {
var temp = myClone(a);
//convert to array
a = [];
for (var i = 0; i < Object.getOwnPropertyNames(temp).length; i++) {
a.push([Object.getOwnPropertyNames(temp)[i], temp[Object.getOwnPropertyNames(temp)[i]]]);
}
return new HashMap(a);
}
HashMap.prototype.put = function (x, y) {
this.a.push([encode(x), y]);
}
HashMap.prototype.get = function (x) {
var t1 = this.a.map((e) => e[0]);
return this.a[t1.indexOf(encode(x))][1];
}
HashMap.prototype.length = function () {
return this.a.length;
}
HashMap.prototype.toString = function () {
var result = [];
for (var i = 0; i < this.length(); i++) {
result.push(JSON.stringify(decode(this.a[i][0]), getCircularReplacer()) + " => " + this.a[i][1]);
}
return "HashMap {" + result + "}";
}
var foo = new HashMap();
foo.put("SQRT3", Math.sqrt(3));
foo.put({}, "bar");
console.log(foo.get({}));
console.log(foo.toString());
Note that it is ordered.
Methods:
put: Adds an item
get: Access an item
from (static): Convert from a JavaScript object
toString: Convert to string
Minified and without the test:
function getNativeClass(t){return void 0===t?"undefined":null===t?"null":Object.prototype.toString.call(t).match(/^\[object\s(.*)\]$/)[1]}function globals(){return"object"==typeof global?global:this}function lookup(t){return globals()[t]}function getAnyClass(t){return void 0===t?"undefined":null===t?"null":t.constructor.name}Function.prototype.toJSON=Function.prototype.toString;var getCircularReplacer=()=>{const t=new WeakSet;return(e,r)=>{if("object"==typeof r&&null!==r){if(t.has(r))return"[Circular]";t.add(r)}return r}};function encode(t){if("object"==typeof t&&null!==t){var e=myClone(t);t=Object.getPrototypeOf(t);for(var r=0;r<Object.getOwnPropertyNames(e).length;r++)t[Object.getOwnPropertyNames(e)[r]]=e[Object.getOwnPropertyNames(e)[r]]}return getAnyClass(t)+" "+JSON.stringify(t,getCircularReplacer())}function decode(t){var e=t.split(" ").slice(1).join(" ");return lookup(t.split(" ")[0]),new(lookup(t.split(" ")[0]))(JSON.parse(e))}function fromEntries(t){return[...t].reduce((t,[e,r])=>(t[e]=r,t),{})}var toEnumerable=t=>fromEntries(Object.getOwnPropertyNames(t).map(e=>[e,t[e]]));function myClone(t){if("object"!=typeof t||!t)return t;const e=Object.assign({},toEnumerable(t)),r=t.constructor;return Object.setPrototypeOf(e,r.prototype),e}function HashMap(t){void 0===t&&(t=[]),t=(t=Array.from(t)).map(t=>[encode(t[0]),t[1]]),this.a=t}HashMap.from=function(t){var e=myClone(t);t=[];for(var r=0;r<Object.getOwnPropertyNames(e).length;r++)t.push([Object.getOwnPropertyNames(e)[r],e[Object.getOwnPropertyNames(e)[r]]]);return new HashMap(t)},HashMap.prototype.put=function(t,e){this.a.push([encode(t),e])},HashMap.prototype.get=function(t){var e=this.a.map(t=>t[0]);return this.a[e.indexOf(encode(t))][1]},HashMap.prototype.length=function(){return this.a.length},HashMap.prototype.toString=function(){for(var t=[],e=0;e<this.length();e++)t.push(JSON.stringify(decode(this.a[e][0]),getCircularReplacer())+" => "+this.a[e][1]);return"HashMap {"+t+"}"};
Also, you can customize the encoder and decoder by changing encode and decode functions.
As in florian's answer, you can't play with the reference in js however (so two empty objects will look like the same to the hashtable).
class Dict{
constructor(){
this.keys = [];
this.values = [];
this.set = this.set.bind(this);
}
set(key, value){
this.keys.push(key);
this.values.push(value);
}
get(key){
return this.values[this.keys.indexOf(key)];
}
all(){
return this.keys.map((kk, ii)=>[kk, this.values[ii]]);
}
}
let d1 = new Dict();
let k1 = {1: 'a'};
d1.set(k1, 2);
console.log(d1.get(k1)); // 2
let k2 = {2: 'b'};
d1.set(k2, 3);
console.log(d1.all());
// [ [ { '1': 'a' }, 2 ], [ { '2': 'b' }, 3 ] ]
Just use the strict equality operator when looking up the object: ===
var objects = [];
objects.push(object1);
objects.push(object2);
objects[0] === object1; // true
objects[1] === object1; // false
The implementation will depend on how you store the objects in the HashTable class.