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Swap javascript object index by name

My javascript object looks like the example below, I am wondering how I should write a swap function to change the element position in the object. For example, I want to swap two elements from position 1 to 2 and 2 to 1.
{
element_name_1 : {
//.. data
}
element_name_2 : {
//.. data
}
element_name_3 : {
//.. data
}
element_name_4 : {
//.. data
}
}
Now I want to swap element_name_2 with element_name_1.

As Miles points out, your code is probably broken and should use an array. I wouldn't use it, nor is it tested, but it is possible.
var data = {
element_name_1: {},
element_name_2: {},
element_name_3: {},
element_name_4: {}
}
console.log(data);
var swap = function(object, key1, key2) {
// Get index of the properties
var pos1 = Object.keys(object).findIndex(x => {
return x === key1
});
var pos2 = Object.keys(object).findIndex(x => {
return x === key2
});
// Create new object linearly with the properties swapped
var newObject = {};
Object.keys(data).forEach((key, idx) => {
if (idx === pos1)
newObject[key2] = object[key2];
else if (idx === pos2)
newObject[key1] = object[key1];
else
newObject[key] = object[key];
});
return newObject;
}
console.log(swap(data, "element_name_1", "element_name_2"));

Have a look at the code, may this solve the problem
function swapFunction(source, destination) {
var tempValu,
sourceIndex;
for ( i = 0; i < Arry.length; i++) {
for (var key in Arry[i]) {
Ti.API.info('key : ' + key);
if (source == key) {
tempValu = Arry[i];
sourceIndex = i;
}
if (destination == key) {
Arry[sourceIndex] = Arry[i];
Arry[i] = tempValu;
return Arry;
}
}
}
}
JSON.stringify(swapFunction("key_1", "key_3")); // [{"key_3":"value_3"},{"key_2":"value_2"},{"key_1":"value_1"},{"key_4":"value_4"},{"key_5":"value_5"}]
Let me know if this works.
Good Luck & Cheers
Ashish Sebastian

How implement javascript Map structure with dynamic data ?

I am trying to create tree like component,
for the first level data is coming from the server ,
if the user clicks the node i need to populate the child nodes with the data from service call.
what is the best way to save the data for this tree component ?
because user will do some operations on the tree component like remove, add & move. Finally i need to send the updated data to the server .

This is the hashmap functionality I use in javascript.
I based it off the docs of java 7 hashmap.
http://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html
I added the load and save variables to allow JSON storage. be careful though. if you stored any complex objects(like a hashmap in a hashmap) you will lose that.
You'd have to implement your own object instantiatiors in the load and save function.
A JSfiddle to play with if you like:
http://jsfiddle.net/mdibbets/s51tubm4/
function HashMap() {
this.map = {};
this.listsize = 0;
}
HashMap.prototype._string = function(key) {
if(typeof key.toString !== 'undefined') {
return key.toString();
}
else {
throw new Error('No valid key supplied. Only supply Objects witha toString() method as keys');
}
}
HashMap.prototype.put = function(key,value) {
key = this._string(key);
if(typeof this.map[key] === 'undefined') {
this.listsize++;
}
this.map[key] = value;
}
HashMap.prototype.get = function(key) {
key = this._string(key);
return this.map[key];
}
HashMap.prototype.containsKey = function(key) {
key = this._string(key);
return !(this.map[key] === 'undefined');
}
HashMap.prototype.putAll = function(hashmap) {
if(hashmap instanceof HashMap) {
var othermap = hashmap.map;
for(var key in othermap) {
if(othermap.hasOwnProperty(key)) {
if(typeof this.map[key] === 'undefined') {
this.listsize++;
}
this.map[key] = othermap[key];
}
}
}
else {
throw new Error('No HashMap instance supplied');
}
}
HashMap.prototype.remove = function(key) {
key = this._string(key);
var ret = null;
if(typeof this.map[key] !== 'undefined') {
ret = this.map[key];
delete this.map[key];
this.listsize--;
}
return ret;
}
HashMap.prototype.clear = function() {
this.map = {};
this.listsize = 0;
}
HashMap.prototype.containsValue = function(value) {
for(var key in this.map) {
if(this.map.hasOwnProperty(key)) {
if(this.map[key] === value) {
return true;
}
}
}
return false;
}
HashMap.prototype.clone = function() {
var ret = new HashMap();
ret.map = this.map;
ret.listsize = this.listsize;
return ret;
}
HashMap.prototype.entrySet = function() {
return this.map;
}
HashMap.prototype.keySet = function() {
var ret = [];
for(var key in this.map) {
if(this.map.hasOwnProperty(key)) {
ret.push(key);
}
}
return ret;
}
HashMap.prototype.values = function() {
var ret = [];
for(var key in this.map) {
if(this.map.hasOwnProperty(key)) {
ret.push(this.map[key]);
}
}
return ret;
}
HashMap.prototype.size = function(activeCheck) {
//Active check is expensive.
if(typeof activeCheck !== 'undefined' && activeCheck) {
var count = 0;
for(var key in this.map) {
if(this.map.hasOwnProperty(key)) {
count++;
}
}
return count;
}
return this.listsize;
}
HashMap.prototype.save = function(){
return JSON.stringify(this.map);
}
HashMap.prototype.load = function(json) {
if(typeof json !== 'string') {
throw new Error("No valid input supplied. Only supply JSON Strings");
}
this.map = JSON.parse(json);
this.listsize = this.size(true);
}
var map = new HashMap();
console.log(
map.put('hello', true),
map.get('hello'),
map.put('hello',10),
map.put('world',20),
map.values(),
map.keySet(),
map.entrySet(),
map.containsValue('twoshoes'),
map.size()
);
var map2 = new HashMap();
map2.put('goody','twoshoes');
map2.putAll(map);
console.log(
map2.get('hello'),
map2.values(),
map2.keySet(),
map2.entrySet(),
map2.containsValue('twoshoes'),
map2.size()
);
var map3 = new HashMap();
map3.load(map2.save());
console.log(
map3.get('hello'),
map3.values(),
map3.keySet(),
map3.entrySet(),
map3.containsValue('twoshoes'),
map3.size()
);

traversing a json for empty array value

i have a below json
{
"loanDetails": [
{
"vehicleDetail": {
"RCBookImageReferences": {
"imagePathReferences": [
{
}
]
}
},
"chargeDetails": [
{
}
],
"commissionDetails": [
{
}
],
"disbursementDetails": [
{
}
]
}
]
}
in the above json i need to traverse every key and if i find it emty then set the parent as empty array ie the output should be as below
{"loanDetails":[]}
i used the code below
function isEmpty(obj) {
for(var prop in obj) {
if(obj.hasOwnProperty(prop))
return false;
}
return true;
}
But it did not give me the expected result.I'm stuck here any help will be much helpful.

The function clean takes an object and loops over its keys, calling clean recursively
on each object-valued property.
If the result of cleaning is an empty object, delete the key in question.
If the object itself turns out to be empty, return undefined, triggering deletion of the property holding that object at the higher level.
function clean(obj) {
var isEmpty = true;
for (var key in obj) {
var val = obj[key];
if (val === null || typeof val !== 'object' || (obj[key] = clean(val))) {
isEmpty = false;
} else {
delete obj[key];
}
}
return isEmpty ? undefined : obj;
}
>> a = { x: 1, b: { y: [] }, c: { d: { } } }
>> clean(a)
<< Object {x: 1}

This should make it recursive. With two solutions.
Solution 1: empty test function
var boolValue = true;
for(var prop in obj) {
if(obj.hasOwnProperty(prop) && typeof obj[prop] === 'object')
{
boolValue = recursiveIsEmpty(obj[prop]);
}
else
{
return false;
}
}
return boolValue ;
//test and set empty string
recursiveIsEmpty(jsonDataObj['loanDetails']) ? jsonDataObj['loanDetails'] = [] : null;
Solution 2 recursive empty function that empties parent obj
function recursiveIsEmpty(obj) {
var boolValue = true;
for(var prop in obj) {
if(obj.hasOwnProperty(prop) && typeof obj[prop] === 'object')
{
boolValue = recursiveIsEmpty(obj[prop]);
if (boolValue)
{
delete obj[prop]; //an object is empty. Delete from parent;
}
}
else
{
return false;
}
}
return boolValue; //returns an empty object
}
recursiveIsEmpty(jsonDataObj['loanDetails']) //returns jsonDataObj['loanDetails'] = [];
This checks if obj has a property that is an object. If so load that object and check it's properties. If not return false, because that will be string or number and that confirms the object is not empty.

Your JSON-string is not valid. When corrected, you can use a reviver function parameter (see MDN) to remove 'empty' arrays (aka properties with criteria you specify).
To be clear, the reviver function takes care of the traversing on all levels of the parsed object. If it returns undefined the property is removed from the object. The reviver used in the snippet thus removes all properties containing arrays with empty objects, or empty arrays.
The snippet demonstrates this.
// json string corrected
var foo = '{"loanDetails": [{"vehicleDetail": {"RCBookImageReferences": '+
'{"imagePathReferences": [{}]}}, "chargeDetails": [{}],'+
'"commissionDetails": [{}],"disbursementDetails": [{}]}]}';
// parse it, using reviver parameter
var fooparsed = JSON.parse( foo,
function (key, value) { //<= reviver here
return (value.length && value.length == 1 &&
value[0] instanceof Object &&
Object.keys(value[0]).length == 0) ||
value instanceof Array && !value.length
? undefined : value;
}
);
// print
Helpers.log2Screen( Object.print(fooparsed) );
<script src="http://kooiinc.github.io/JSHelpers/Helpers-min.js"></script>

if you are doing this using ajax then you should go with seriallizing the jason array using javascript.
at the time of passing data through json
data: "your data",
use this
data:$(form).serialize(),
it will pass all the key of that form which you are passing ,
if you want to see its result the try to print it on console

var inputObj = {
"loanDetails": [{
"vehicleDetail": {
"RCBookImageReferences": {
"imagePathReferences": [{}]
}
},
"chargeDetails": [{}],
"commissionDetails": [{}],
"disbursementDetails": [{}]
}, {
"vehicleDetail": {
"RCBookImageReferences": {
"imagePathReferences": [{
"Valid": "Working"
}]
}
},
"chargeDetails": [{}],
"commissionDetails": [{}],
"disbursementDetails": [{}]
}],
"Superman": {
"Name": ""
},
"SpiderMan": {
"Name": "Senthil"
}
}
function flatten(target, opts) {
var output = {},
opts = opts || {},
delimiter = opts.delimiter || '.'
function getkey(key, prev) {
return prev ? prev + delimiter + key : key
};
function step(object, prev) {
Object.keys(object).forEach(function(key) {
var isarray = opts.safe && Array.isArray(object[key]),
type = Object.prototype.toString.call(object[key]),
isobject = (type === "[object Object]" || type === "[object Array]")
if (!isarray && isobject) {
return step(object[key], getkey(key, prev))
}
output[getkey(key, prev)] = object[key]
});
if (Object.keys(object) == "") {
if (object instanceof Array) {
output[prev] = [];
} else {
output[prev] = {};
}
}
};
step(target)
return output
};
function unflatten(target, opts) {
var opts = opts || {},
delimiter = opts.delimiter || '.',
result = {}
if (Object.prototype.toString.call(target) !== '[object Object]') {
return target
}
function getkey(key) {
var parsedKey = parseInt(key)
return (isNaN(parsedKey) ? key : parsedKey)
};
Object.keys(target).forEach(function(key) {
var split = key.split(delimiter),
firstNibble, secondNibble, recipient = result
firstNibble = getkey(split.shift())
secondNibble = getkey(split[0])
while (secondNibble !== undefined) {
if (recipient[firstNibble] === undefined) {
recipient[firstNibble] = ((typeof secondNibble === 'number') ? [] : {})
}
recipient = recipient[firstNibble]
if (split.length > 0) {
firstNibble = getkey(split.shift())
secondNibble = getkey(split[0])
}
}
// unflatten again for 'messy objects'
recipient[firstNibble] = unflatten(target[key])
});
//Array Check
var keys = Object.keys(result);
if (keys.length > 0 && keys[0] === "0") {
var output = [];
keys.forEach(function(key) {
output.push(result[key])
});
return output;
}
return result
};
var flatted = flatten(inputObj);
var keys = Object.keys(flatted);
keys.forEach(function(key) {
if (JSON.stringify(flatted[key]) === "{}" || JSON.stringify(flatted[key]) == "") {
// console.log(key)
delete flatted[key];
var paths = key.split(".");
if (paths.length >= 2) {
var int = parseInt(paths[1])
if (isNaN(int)) {
key = paths[0];
flatted[key] = {};
} else {
key = paths[0] + "." + int;
flatted[key] = {};
}
var newKeys = Object.keys(flatted);
for (var j = 0; j < newKeys.length; j++) {
var omg = newKeys[j];
if (omg.indexOf(key) != -1 && omg.length > key.length) {
delete flatted[key];
}
}
}
}
})
console.log(flatted)
var output = unflatten(flatted);
alert(JSON.stringify(output))

Easy way to get multi-level javascript object property

I always need to deal with multi-level js objects where existence of properties are not certain:
try { value1 = obj.a.b.c; } catch(e) { value1 = 1; }
try { value2 = obj.d.e.f; } catch(e) { value2 = 2; }
......
Is there an easier way or a generic function (e.g. ifnull(obj.d.e.f, 2) ) that does not require a lot of try catches?

var value1 = (obj.a && obj.a.b && obj.a.b.c) || 1;
http://jsfiddle.net/DerekL/UfJEQ/
Or use this:
function ifNull(obj, key, defVal){
var keys = key.split("."), value;
for(var i = 0; i < keys.length; i++){
if(typeof obj[keys[i]] !== "undefined"){
value = obj = obj[keys[i]];
}else{
return defVal;
}
}
return value;
}
var value1 = ifNull(obj, "a.b.c", 1);

You could always create a helper function.
function isUndefined(root, path, defaultVal) {
var parts = path.split('.'),
i = 0,
len = parts.length,
o = root || {}, v;
while ((typeof (v = o[parts[i]]) === 'object', o = v) && ++i < len);
return (typeof v === 'undefined' || i !== len)? defaultVal: v;
}
var obj = {a: { b: { test: 'test' }}}, v;
v = isUndefined(obj, 'a.b.test', 1); //test
v = isUndefined(obj, 'a.test', 1); //1

Using lodash you can do this easily**(node exists and empty check for that node)**..
var lodash = require('lodash-contrib');
function invalidateRequest(obj, param) {
var valid = true;
param.forEach(function(val) {
if(!lodash.hasPath(obj, val)) {
valid = false;
} else {
if(lodash.getPath(obj, val) == null || lodash.getPath(obj, val) == undefined || lodash.getPath(obj, val) == '') {
valid = false;
}
}
});
return valid;
}
Usage:
leaveDetails = {
"startDay": 1414998000000,
"endDay": 1415084400000,
"test": { "test1" : 1234 }
};
var validate;
validate = invalidateRequest(leaveDetails, ['startDay', 'endDay', 'test.test1']);
it will return boolean.

JS: How to return 'undefined' instead of throwing error 'cannot read property x of undefined'

What is the best way to have js return undefined rather than throw an error when a parent property does not exist?
Example
a = {}
b = a.x.y.z
// Error: Cannot read property 'value' of undefined
// Target result: b = undefined

You have to check for the existence of each property:
var b;
if (a.x && a.x.y && a.x.y.z) {
b = a.x.y.z
}
Or, simliar to another poster's "safeGet" function:
var get = function (obj, ns) {
var y = ns.split('.');
for(var i = 0; i < y.length; i += 1) {
if (obj[y[i]]) {
obj = obj[y[i]];
} else {
return;
}
}
return obj;
};
Use:
var b = get(a, 'x.y.z');

try {
a = {}
b = a.x.y.z
}
catch (e) {
b = void 0;
}

I would go for slightly verbose:
var b = ((a.x || {}).y || {}).z

you could write a safeGet helper function, something like:
edited for drilldown as suggested in comments by arcyqwerty
var getter = function (collection, key) {
if (collection.hasOwnProperty(key)) {
return collection[key];
} else {
return undefined;
}
};
var drillDown = function (keys, currentIndex, collection) {
var max = keys.length - 1;
var key = keys[currentIndex];
if (typeof collection === 'undefined') {
return undefined;
}
if (currentIndex === max) {
return getter(collection, key);
} else {
return drillDown(keys, currentIndex + 1,
getter(collection, key));
}
};
var safeGet = function (collection, key) {
if (key.indexOf(".") !== -1) {
return drillDown(key.split("."), 0, collection);
} else {
return getter(collection, key);
}
};
a = { x: 1 };
b = safeGet(a, 'x.y.z');
http://jsfiddle.net/YqdWH/2/