We Keep Coding

Create object from multiple object with same value in map JS [duplicate]

I have an array of objects:
[
{ key : '11', value : '1100', $$hashKey : '00X' },
{ key : '22', value : '2200', $$hashKey : '018' }
];
How do I convert it into the following by JavaScript?
{
"11": "1100",
"22": "2200"
}

Tiny ES6 solution can look like:
var arr = [{key:"11", value:"1100"},{key:"22", value:"2200"}];
var object = arr.reduce(
(obj, item) => Object.assign(obj, { [item.key]: item.value }), {});
console.log(object)
Also, if you use object spread, than it can look like:
var object = arr.reduce((obj, item) => ({...obj, [item.key]: item.value}) ,{});
One more solution that is 99% faster is(tested on jsperf):
var object = arr.reduce((obj, item) => (obj[item.key] = item.value, obj) ,{});
Here we benefit from comma operator, it evaluates all expression before comma and returns a last one(after last comma). So we don't copy obj each time, rather assigning new property to it.

This should do it:
var array = [
{ key: 'k1', value: 'v1' },
{ key: 'k2', value: 'v2' },
{ key: 'k3', value: 'v3' }
];
var mapped = array.map(item => ({ [item.key]: item.value }) );
var newObj = Object.assign({}, ...mapped );
console.log(newObj );
One-liner:
var newObj = Object.assign({}, ...(array.map(item => ({ [item.key]: item.value }) )));

You're probably looking for something like this:
// original
var arr = [
{key : '11', value : '1100', $$hashKey : '00X' },
{key : '22', value : '2200', $$hashKey : '018' }
];
//convert
var result = {};
for (var i = 0; i < arr.length; i++) {
result[arr[i].key] = arr[i].value;
}
console.log(result);

I like the functional approach to achieve this task:
var arr = [{ key:"11", value:"1100" }, { key:"22", value:"2200" }];
var result = arr.reduce(function(obj,item){
obj[item.key] = item.value;
return obj;
}, {});
Note: Last {} is the initial obj value for reduce function, if you won't provide the initial value the first arr element will be used (which is probably undesirable).
https://jsfiddle.net/GreQ/2xa078da/

Using Object.fromEntries:
const array = [
{ key: "key1", value: "value1" },
{ key: "key2", value: "value2" },
];
const obj = Object.fromEntries(array.map(item => [item.key, item.value]));
console.log(obj);

A clean way to do this using modern JavaScript is as follows:
const array = [
{ name: "something", value: "something" },
{ name: "somethingElse", value: "something else" },
];
const newObject = Object.assign({}, ...array.map(item => ({ [item.name]: item.value })));
// >> { something: "something", somethingElse: "something else" }

you can merge array of objects in to one object in one line:
const obj = Object.assign({}, ...array);

Use lodash!
const obj = _.keyBy(arrayOfObjects, 'keyName')

Update: The world kept turning. Use a functional approach instead.
Previous answer
Here you go:
var arr = [{ key: "11", value: "1100" }, { key: "22", value: "2200" }];
var result = {};
for (var i=0, len=arr.length; i < len; i++) {
result[arr[i].key] = arr[i].value;
}
console.log(result); // {11: "1000", 22: "2200"}

Simple way using reduce
// Input :
const data = [{key: 'value'}, {otherKey: 'otherValue'}];
data.reduce((prev, curr) => ({...prev, ...curr}) , {});
// Output
{key: 'value', otherKey: 'otherValue'}
More simple Using Object.assign
Object.assign({}, ...array);

Using Underscore.js:
var myArray = [
Object { key="11", value="1100", $$hashKey="00X"},
Object { key="22", value="2200", $$hashKey="018"}
];
var myObj = _.object(_.pluck(myArray, 'key'), _.pluck(myArray, 'value'));

Nearby 2022, I like this approach specially when the array of objects are dynamic which also suggested based on #AdarshMadrecha's test case scenario,
const array = [
{ key : '11', value : '1100', $$hashKey : '00X' },
{ key : '22', value : '2200', $$hashKey : '018' }];
let obj = {};
array.forEach( v => { obj[v.key] = v.value }) //assign to new object
console.log(obj) //{11: '1100', 22: '2200'}

let array = [
{ key: "key1", value: "value1" },
{ key: "key2", value: "value2" },
];
let arr = {};
arr = array.map((event) => ({ ...arr, [event.key]: event.value }));
console.log(arr);

Was did yesterday
// Convert the task data or array to the object for use in the above form
const {clientData} = taskData.reduce((obj, item) => {
// Use the clientData (You can set your own key name) as the key and the
// entire item as the value
obj['clientData'] = item
return obj
}, {});

Here's how to dynamically accept the above as a string and interpolate it into an object:
var stringObject = '[Object { key="11", value="1100", $$hashKey="00X"}, Object { key="22", value="2200", $$hashKey="018"}]';
function interpolateStringObject(stringObject) {
var jsObj = {};
var processedObj = stringObject.split("[Object { ");
processedObj = processedObj[1].split("},");
$.each(processedObj, function (i, v) {
jsObj[v.split("key=")[1].split(",")[0]] = v.split("value=")[1].split(",")[0].replace(/\"/g,'');
});
return jsObj
}
var t = interpolateStringObject(stringObject); //t is the object you want
http://jsfiddle.net/3QKmX/1/

// original
var arr = [{
key: '11',
value: '1100',
$$hashKey: '00X'
},
{
key: '22',
value: '2200',
$$hashKey: '018'
}
];
// My solution
var obj = {};
for (let i = 0; i < arr.length; i++) {
obj[arr[i].key] = arr[i].value;
}
console.log(obj)

You can use the mapKeys lodash function for that. Just one line of code!
Please refer to this complete code sample (copy paste this into repl.it or similar):
import _ from 'lodash';
// or commonjs:
// const _ = require('lodash');
let a = [{ id: 23, title: 'meat' }, { id: 45, title: 'fish' }, { id: 71, title: 'fruit' }]
let b = _.mapKeys(a, 'id');
console.log(b);
// b:
// { '23': { id: 23, title: 'meat' },
// '45': { id: 45, title: 'fish' },
// '71': { id: 71, title: 'fruit' } }

JavaScript get unique array object data by 2 object unique

I have problem with find uniqueness by 2 value. I want do something like SQL GROUP BY Tag_No and PlatformID. I want find unique value by Tag_No and PlayformID where both value can't be duplicate
I have tried something like below, but it only works for one unique 'Tag_No'
var NewTag = [
{Tag_No:'xxx01',PlatformID:'12',Details:'example1'},
{Tag_No:'xxx02',PlatformID:'13',Details:'example2'},
{Tag_No:'xxx03',PlatformID:'14',Details:'example3'},
{Tag_No:'xxx05',PlatformID:'5',Details:'example4'},
{Tag_No:'xxx05',PlatformID:'12',Details:'example5'},
{Tag_No:'xxx05',PlatformID:'12',Details:'example6'},
]
var tmp = [];
var result = [];
if (NewTag !== [] /* any additional error checking */ ) {
for (var i = 0; i < NewTag.length; i++) {
var val = NewTag[i];
if (tmp[val.Tag_No] === undefined ) {
tmp[val.Tag_No] = true;
result.push(val);
}
}
}
console.log('result',result)
expected value is
result=[{Tag_No:'xxx01',PlatformID:'12',Details:'example1'},
{Tag_No:'xxx02',PlatformID:'13',Details:'example2'},
{Tag_No:'xxx03',PlatformID:'14',Details:'example3'},
{Tag_No:'xxx05',PlatformID:'5',Details:'example4'},
{Tag_No:'xxx05',PlatformID:'12',Details:'example5'},
]

use array.filter instead.
This filters your array on duplicates no matter what structure you have.
Reference
var NewTag = [
{Tag_No:'xxx01',PlatformID:'12',Details:'example'},
{Tag_No:'xxx02',PlatformID:'13',Details:'example'},
{Tag_No:'xxx03',PlatformID:'14',Details:'example'},
{Tag_No:'xxx05',PlatformID:'5',Details:'example'},
{Tag_No:'xxx05',PlatformID:'12',Details:'example'},
{Tag_No:'xxx05',PlatformID:'12',Details:'example'},
]
const uniqueArray = NewTag.filter((value, index) => {
const _value = JSON.stringify(value);
return index === NewTag.findIndex(obj => {
return JSON.stringify(obj) === _value;
});
});
console.log('result',uniqueArray)

You can use hash grouping approach:
const data = [{Tag_No:'xxx01',PlatformID:'12',Details:'example'},{Tag_No:'xxx02',PlatformID:'13',Details:'example'},{Tag_No:'xxx03',PlatformID:'14',Details:'example'},{Tag_No:'xxx05',PlatformID:'5',Details:'example'},{Tag_No:'xxx05',PlatformID:'12',Details:'example'},{Tag_No:'xxx05',PlatformID:'12',Details:'example'}];
const result = Object.values(data.reduce((acc, item) => {
const hash = [item.Tag_No, item.PlatformID].join('---');
acc[hash] ??= item;
return acc;
}, {}));
console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0 }

Here is my solution:
let NewTag = [
{Tag_No:'xxx01',PlatformID:'12',Details:'example'},
{Tag_No:'xxx02',PlatformID:'13',Details:'example'},
{Tag_No:'xxx03',PlatformID:'14',Details:'example'},
{Tag_No:'xxx05',PlatformID:'5',Details:'example'},
{Tag_No:'xxx05',PlatformID:'12',Details:'example'},
{Tag_No:'xxx05',PlatformID:'12',Details:'example'},
]
let temp=[]
let result=[];
NewTag.forEach(tag=>{
let key=tag.Tag_No+"\t"+tag.PlatformID;
if (!temp.includes(key)){
temp.push(key);
result.push(tag)
}
});
console.log(result)

You could use Set to check for uniqueness
const NewTag = [
{ Tag_No: "xxx01", PlatformID: "12", Details: "example" },
{ Tag_No: "xxx02", PlatformID: "13", Details: "example" },
{ Tag_No: "xxx03", PlatformID: "14", Details: "example" },
{ Tag_No: "xxx05", PlatformID: "5", Details: "example" },
{ Tag_No: "xxx05", PlatformID: "12", Details: "example" },
{ Tag_No: "xxx05", PlatformID: "12", Details: "example" },
]
const uniquePairSet = new Set()
const res = NewTag.reduce((acc, el) => {
const Tag_No_PlatformID = `${el.Tag_No}-${el.PlatformID}`
if (!uniquePairSet.has(Tag_No_PlatformID)) {
uniquePairSet.add(Tag_No_PlatformID)
acc.push(el)
}
return acc
}, [])
console.log("result", res)
References
Set

re-organizing array of objects

So I have an array of objects that contain information for different activities in different projects.
It looks something like this
const input = [
{
Project: 1,
ID: "1-1",
},
{
Project: 1,
ID: "1-2",
},
{
Project: 2,
ID: "2-1",
},
];
From this, I would like to go to this
output = [{
Project: 1,
ID1: 1 - 1,
ID2: 1 - 2,
},
{
Project: 1,
ID1: 2 - 1,
},
];
Here's what I have so far:
let currentProject = ''
let output = []
for (const e of input) {
let counter
let outputObj = {}
if (currentProject !== e.Project) {
output.push(outputObj)
counter = 1
outputObj = {}
outputObj.projectNum = e.Project
currentProject = e.Project
}
if (currentProject == e.Project) {
outputObj['ID' + counter] = e.ID
counter++
}
}
here's what I'm getting back:
output = [{
Project: 1,
ID1: 1 - 1
},
{
Project: 1,
ID1: 2 - 1
}
]
I'm not sure what the issue is, tried several times to fix it.
Could someone please help me get over the edge?
Any help will be greatly appreciated.

You can achieve this using reduce, Object.keys
const input = [{
Project: 1,
ID: "1-1",
},
{
Project: 1,
ID: "1-2",
},
{
Project: 2,
ID: "2-1",
},
];
const result = input.reduce((acc, curr) => {
const { Project, ID } = curr;
const obj = acc.find((el) => el.Project === Project);
if (obj) {
const length = Object.keys(obj).length;
obj[`ID${length}`] = ID;
} else {
acc.push({ Project, [`ID${1}`]: ID });
}
return acc;
}, []);
console.log(result);

You can try this.
const input=[{Project:1,ID:"1-1",},{Project:1,ID:"1-2",},{Project:2,ID:"2-1"}];
let temp = {};
input.map(v=>(temp[v.Project] ??= []).push(v.ID));
let output = Object.keys(temp).map(k=>{
let json = {Project:k};
temp[k].map((v,k)=>json['ID'+(Number(k+1))]=v);
return json;
});
console.log(output);
you will get the result.
[
{ Project: '1', ID1: '1-1', ID2: '1-2' },
{ Project: '2', ID1: '2-1' }
]

The way you intended to implement this assumes every project from same id comes sequentially grouped.
While #decpk answer deals with with a linear search, for performance reasons I would rather first use a dictionary and then convert to an array, AND also keep track of id quantities using a field n.
const input = [
{
Project: 1,
ID: "1-1",
},
{
Project: 1,
ID: "1-2",
},
{
Project: 2,
ID: "2-1",
},
];
const projects = {}
for (const e of input) {
let pid = e.Project
let project = projects[pid]
//First time seeing this project
if (!project) {
projects[pid] = { Project: pid, n: 1, ID1: e.ID }
}
//insert more ID
else {
project.n += 1
project[`ID${project.n}`] = e.ID
}
}
//And now converting the object to array, removing the 'n' field
const output = Object.keys(projects).map(pid => {
const obj = projects[pid]
delete obj.n
obj.Project = pid
return obj
})

You can try this way - O(n) time complexity
Using reduce to aggregate data.
Using logical nullish assignment only assigns if acc[Project] is nullish (null or undefined).
Define each additional key-value pair like:
const number = Object.keys(acc[Project]).length; // Define key format by number of existing property.
const key = `ID${number}`;
instead of using count variable.
const input=[{Project:1,ID:"1-1",},{Project:1,ID:"1-2",},{Project:2,ID:"2-1",}];
const output = input.reduce((acc, {Project, ID}) =>
{
acc[Project] ??= {Project}; // Get exist object or create new one
const number = Object.keys(acc[Project]).length; // Define key format by number of existing property.
const key = `ID${number}`;
acc[Project][key] = ID;
return acc;
}, {});
console.log(Object.values(output));
Output:
[
{
"Project": 1,
"ID1": "1-1",
"ID2": "1-2"
},
{
"Project": 2,
"ID1": "2-1"
}
]

Find Duplicate Array By Caption without using multiple loops [duplicate]

I need some help with iterating through array, I keep getting stuck or reinventing the wheel.
values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName1' },
{ name: 'someName1' }
]
How could I check if there are two (or more) same name value in array? I do not need a counter, just setting some variable if array values are not unique. Have in mind that array length is dynamic, also array values.

Use array.prototype.map and array.prototype.some:
var values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName2' }
];
var valueArr = values.map(function(item){ return item.name });
var isDuplicate = valueArr.some(function(item, idx){
return valueArr.indexOf(item) != idx
});
console.log(isDuplicate);

ECMA Script 6 Version
If you are in an environment which supports ECMA Script 6's Set, then you can use Array.prototype.some and a Set object, like this
let seen = new Set();
var hasDuplicates = values.some(function(currentObject) {
return seen.size === seen.add(currentObject.name).size;
});
Here, we insert each and every object's name into the Set and we check if the size before and after adding are the same. This works because Set.size returns a number based on unique data (set only adds entries if the data is unique). If/when you have duplicate names, the size won't increase (because the data won't be unique) which means that we would have already seen the current name and it will return true.
ECMA Script 5 Version
If you don't have Set support, then you can use a normal JavaScript object itself, like this
var seen = {};
var hasDuplicates = values.some(function(currentObject) {
if (seen.hasOwnProperty(currentObject.name)) {
// Current name is already seen
return true;
}
// Current name is being seen for the first time
return (seen[currentObject.name] = false);
});
The same can be written succinctly, like this
var seen = {};
var hasDuplicates = values.some(function (currentObject) {
return seen.hasOwnProperty(currentObject.name)
|| (seen[currentObject.name] = false);
});
Note: In both the cases, we use Array.prototype.some because it will short-circuit. The moment it gets a truthy value from the function, it will return true immediately, it will not process rest of the elements.

In TS and ES6 you can create a new Set with the property to be unique and compare it's size to the original array.
const values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName3' },
{ name: 'someName1' }
]
const uniqueValues = new Set(values.map(v => v.name));
if (uniqueValues.size < values.length) {
console.log('duplicates found')
}

To know if simple array has duplicates we can compare first and last indexes of the same value:
The function:
var hasDupsSimple = function(array) {
return array.some(function(value) { // .some will break as soon as duplicate found (no need to itterate over all array)
return array.indexOf(value) !== array.lastIndexOf(value); // comparing first and last indexes of the same value
})
}
Tests:
hasDupsSimple([1,2,3,4,2,7])
// => true
hasDupsSimple([1,2,3,4,8,7])
// => false
hasDupsSimple([1,"hello",3,"bye","hello",7])
// => true
For an array of objects we need to convert the objects values to a simple array first:
Converting array of objects to the simple array with map:
var hasDupsObjects = function(array) {
return array.map(function(value) {
return value.suit + value.rank
}).some(function(value, index, array) {
return array.indexOf(value) !== array.lastIndexOf(value);
})
}
Tests:
var cardHand = [
{ "suit":"spades", "rank":"ten" },
{ "suit":"diamonds", "rank":"ace" },
{ "suit":"hearts", "rank":"ten" },
{ "suit":"clubs", "rank":"two" },
{ "suit":"spades", "rank":"three" },
]
hasDupsObjects(cardHand);
// => false
var cardHand2 = [
{ "suit":"spades", "rank":"ten" },
{ "suit":"diamonds", "rank":"ace" },
{ "suit":"hearts", "rank":"ten" },
{ "suit":"clubs", "rank":"two" },
{ "suit":"spades", "rank":"ten" },
]
hasDupsObjects(cardHand2);
// => true

if you are looking for a boolean, the quickest way would be
var values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName1' },
{ name: 'someName1' }
]
// solution
var hasDuplicate = false;
values.map(v => v.name).sort().sort((a, b) => {
if (a === b) hasDuplicate = true
})
console.log('hasDuplicate', hasDuplicate)

const values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName4' }
];
const foundDuplicateName = values.find((nnn, index) =>{
return values.find((x, ind)=> x.name === nnn.name && index !== ind )
})
console.log(foundDuplicateName)
Found the first one duplicate name
const values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName4' }
];
const foundDuplicateName = values.find((nnn, index) =>{
return values.find((x, ind)=> x.name === nnn.name && index !== ind )
})

You just need one line of code.
var values = [
{ name: 'someName1' },
{ name: 'someName2' },
{ name: 'someName4' },
{ name: 'someName2' }
];
let hasDuplicates = values.map(v => v.name).length > new Set(values.map(v => v.name)).size ? true : false;

Try an simple loop:
var repeat = [], tmp, i = 0;
while(i < values.length){
repeat.indexOf(tmp = values[i++].name) > -1 ? values.pop(i--) : repeat.push(tmp)
}
Demo

With Underscore.js A few ways with Underscore can be done. Here is one of them. Checking if the array is already unique.
function isNameUnique(values){
return _.uniq(values, function(v){ return v.name }).length == values.length
}
With vanilla JavaScript
By checking if there is no recurring names in the array.
function isNameUnique(values){
var names = values.map(function(v){ return v.name });
return !names.some(function(v){
return names.filter(function(w){ return w==v }).length>1
});
}

//checking duplicate elements in an array
var arr=[1,3,4,6,8,9,1,3,4,7];
var hp=new Map();
console.log(arr.sort());
var freq=0;
for(var i=1;i<arr.length;i++){
// console.log(arr[i-1]+" "+arr[i]);
if(arr[i]==arr[i-1]){
freq++;
}
else{
hp.set(arr[i-1],freq+1);
freq=0;
}
}
console.log(hp);

You can use map to return just the name, and then use this forEach trick to check if it exists at least twice:
var areAnyDuplicates = false;
values.map(function(obj) {
return obj.name;
}).forEach(function (element, index, arr) {
if (arr.indexOf(element) !== index) {
areAnyDuplicates = true;
}
});
Fiddle

Adding updated es6 function to check for unique and duplicate values in array. This function is modular and can be reused throughout the code base. Thanks to all the post above.
/* checks for unique keynames in array */
const checkForUnique = (arrToCheck, keyName) => {
/* make set to remove duplicates and compare to */
const uniqueValues = [...new Set(arrToCheck.map(v => v[keyName]))];
if(arrToCheck.length !== uniqueValues.length){
console.log('NOT UNIQUE')
return false
}
return true
}
let arr = [{name:'joshua'},{name:'tony'},{name:'joshua'}]
/* call function with arr and key to check for */
let isUnique = checkForUnique(arr,'name')

checkDuplicate(arr, item) {
const uniqueValues = new Set(arr.map((v) => v[item]));
return uniqueValues.size < arr.length;
},
console.log(this.checkDuplicate(this.dutyExemptionBase, 'CI_ExemptionType')); // true || false

It is quite interesting to work with arrays
You can use new Set() method to find duplicate values!
let's assume you have an array of objects like this...
let myArray = [
{ id: 0, name: "Jhon" },
{ id: 1, name: "sara" },
{ id: 2, name: "pop" },
{ id: 3, name: "sara" }
]
const findUnique = new Set(myArray.map(x => {
return x.name
}))
if(findUnique.size < myArray.length){
console.log("duplicates found!")
}else{
console.log("Done!")
}

const duplicateValues = [{ name: "abc" }, { name: "bcv" }, { name: "abc" }];
const isContainDuplicate = (params) => {
const removedDuplicate = new Set(params.map((el) => el.name));
return params.length !== removedDuplicate.size;
};
const isDuplicate = isContainDuplicate(duplicateValues);
console.log("isDuplicate");

Get parent array key in deep nested object using lodash

I'm using Lodash JavaScript library in my project and have a problem in getting the parent array key object filtered object:
I've the following data:
var data = {
5: [{
id: "3",
label: "Manish"
}, {
id: "6",
label: "Rahul"
}, {
id: "7",
label: "Vikash"
}],
8: [{
id: "16",
label: "Pankaj"
}, {
id: "45",
label: "Akash"
}],
9: [{
id: "15",
label: "Sunil"
}]
}
My requirement is if I've the array of [6,16] then I want a new result array containing values 5,8 because these two array keys have objects which contain id:"6" and id:"16"
I tried it using _.flatten and _.pick method but could not work. I used the following code;
var list = [];
_.each(data, function(item){
list.push(_.omit(item, 'id'));
list.push(_.flatten(_.pick(item, 'id')));
});
var result = _.flatten(list);
console.log(result);

var res = _([6, 16]).map(function(id){
return _.findKey(data, function(arr){
return _.some(arr, {id: new String(id)});
})
}).compact().uniq().value();

If simple javascript solution is okay with you then
var searchId=[6,16];
var newArr = [];
for ( key in data ){
data[key].forEach( function(innerValue){
if ( searchId.indexOf( Number(innerValue.id) ) != -1 ) newArr.push( key );
} );
}
console.log(newArr);

try this:
( hope im not missing some syntax )
var result = [];
var filterArray = [6,16];
_.each(filterArray, function(item){
_.merge(result,_.filter(data, function(o) { return _.contains(o,{id:item}) }));
});

Using _.pickBy this problem is solved simply:
var myArr = [6, 16]
var res = _.pickBy(data, function (value) {
return _(value).map('id').map(_.toNumber).intersection(myArr).size();
});
console.log(res)
https://jsfiddle.net/7s4s7h3w/