var items = [
  {
    "name": "Crossix Belarus - Crossix Solutions BY",
    "id": 63,
    "parent": 59,
    "currency": 1
  },
  {
    "name": "Crossix Israel - Crossix Solutions LTD.",
    "id": 64,
    "parent": 59,
    "currency": 1
  },
  {
    "name": "Veeva Systems Inc.",
    "id": 1,
    "parent": null,
    "currency": 1
  },
  {
    "name": "Veeva EMEA",
    "id": 2,
    "parent": 1,
    "currency": 4
  },
  {
    "name": "SPAIN - Veeva Systems Spain S.L.",
    "id": 4,
    "parent": 3,
    "currency": 4
  },
  {
    "name": "UK - Veeva Systems UK Ltd.",
    "id": 3,
    "parent": 2,
    "currency": 2
  },
  {
    "name": "CHINA - Veeva Systems, Software (Shanghai) Company Ltd.",
    "id": 5,
    "parent": 1,
    "currency": 5
  },
  {
    "name": "JAPAN - Veeva Japan Kabushiki Kaisha",
    "id": 6,
    "parent": 1,
    "currency": 6
  },
  {
    "name": "ELIMINATION - UK",
    "id": 7,
    "parent": 3,
    "currency": 2
  },
  {
    "name": "ELIMINATION - U.S.",
    "id": 8,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "MEXICO - Veeva Services, S. De R.L. De C.V.",
    "id": 57,
    "parent": 56,
    "currency": 1
  },
  {
    "name": "MEXICO - Veeva, S. De R.L. De C.V.",
    "id": 58,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "Crossix US - Crossix Solutions Inc.",
    "id": 59,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "ISRAEL - Veeva Systems, Inc.",
    "id": 30,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "Veeva Property Holding LLC",
    "id": 31,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "THAILAND - Veeva Systems Inc.",
    "id": 32,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "SWITZERLAND - Veeva Switzerland GmbH",
    "id": 33,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "UKRAINE - Veeva Systems Ukraine Limited",
    "id": 34,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "Veeva (Mederi) GmbH",
    "id": 35,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "INDIA - Veeva Software System India Private Limited",
    "id": 36,
    "parent": 1,
    "currency": 18
  },
  {
    "name": "Veeva UK Holding Company - UKHL",
    "id": 37,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "Zinc Ahead Inc.",
    "id": 39,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "JAPAN - Zinc Ahead KK",
    "id": 41,
    "parent": 6,
    "currency": 6
  },
  {
    "name": "AUSTRALIA - Veeva Australia Pty Ltd (NEW)",
    "id": 42,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "AUSTRALIA - Zinc Ahead Pty Ltd",
    "id": 43,
    "parent": 42,
    "currency": 1
  },
  {
    "name": "UK - Zinc Ahead Holdings Ltd",
    "id": 48,
    "parent": 47,
    "currency": 2
  },
  {
    "name": "UK - Mineral Newco Ltd",
    "id": 47,
    "parent": 37,
    "currency": 2
  },
  {
    "name": "UK - Zinc Ahead Ltd",
    "id": 49,
    "parent": 48,
    "currency": 2
  },
  {
    "name": "Veeva Systems Korea YH",
    "id": 52,
    "parent": 1,
    "currency": 16
  },
  {
    "name": "AUSTRALIA - Veeva Australia Pty Ltd",
    "id": 9,
    "parent": 1,
    "currency": 9
  },
  {
    "name": "BELGIUM - Veeva Systems Belgium DNU",
    "id": 54,
    "parent": 1,
    "currency": 4
  },
  {
    "name": "BELGIUM - Veeva Systems Belgium",
    "id": 55,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "Veeva Holding Inc.",
    "id": 56,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "BRAZIL - Veeva Brasil Desenvolvimento De Sistemas Ltda",
    "id": 19,
    "parent": 1,
    "currency": 12
  },
  {
    "name": "CANADA - Veeva Software Systems Inc.",
    "id": 21,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "SINGAPORE - VEEVA SYSTEMS SINGAPORE PTE. LTD.",
    "id": 12,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "ITALY - BRANCH OFFICE OF VEEVA SYSTEMS INC",
    "id": 13,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "GERMANY - Veeva Systems GmbH",
    "id": 15,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "AMS",
    "id": 16,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "HUNGARY - VEEVA Systems Hungary Kft.",
    "id": 10,
    "parent": 1,
    "currency": 8
  },
  {
    "name": "FRANCE - VEEVA SYSTEMS FRANCE SARL",
    "id": 11,
    "parent": 1,
    "currency": 4
  },
  {
    "name": "FRANCE - VEEVA SYSTEMS FRANCE SARL - NEW",
    "id": 66,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "SPAIN - Veeva Systems Spain S.L. - NEW",
    "id": 69,
    "parent": 68,
    "currency": 1
  },
  {
    "name": "HUNGARY - VEEVA Systems Hungary Kft. - NEW",
    "id": 65,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "UK - Veeva Systems UK Ltd. - NEW",
    "id": 68,
    "parent": 1,
    "currency": 1
  },
  {
    "name": "SINGAPORE - VEEVA SYSTEMS SINGAPORE PTE. LTD. - NEW",
    "id": 70,
    "parent": 1,
    "currency": 11
  }
];
function unflatten(items) {
  var tree = [],
      mappedArr = {}
      
  // Build a hash table and map items to objects
  items.forEach(function(item) {
    var id = item.id;
    if (!mappedArr.hasOwnProperty(id)) { // in case of duplicates
      mappedArr[id] = item; // the extracted id as key, and the item as value
      mappedArr[id].children = [];  // under each item, add a key "children" with an empty array as value
    }
  })
  
  // Loop over hash table
  for (var id in mappedArr) { 
    if (mappedArr.hasOwnProperty(id)) {
      mappedElem = mappedArr[id];
      
      // If the element is not at the root level, add it to its parent array of children. Note this will continue till we have only root level elements left
      if (mappedElem.parent) { 
        var parentId = mappedElem.parent;
        mappedArr[parentId].children.push(mappedElem); 
      }
      
      // If the element is at the root level, directly push to the tree
      else { 
        tree.push(mappedElem);
      } 
    }
  }
  
  return tree;
  
}
var result = unflatten(items);
var maindataarray = JSON.stringify(result);
console.log(maindataarray);

Javascript Online Compiler

Write, Run & Share Javascript code online using OneCompiler's JS online compiler for free. It's one of the robust, feature-rich online compilers for Javascript language. Getting started with the OneCompiler's Javascript editor is easy and fast. The editor shows sample boilerplate code when you choose language as Javascript and start coding.

About Javascript

Javascript(JS) is a object-oriented programming language which adhere to ECMA Script Standards. Javascript is required to design the behaviour of the web pages.

Key Features

  • Open-source
  • Just-in-time compiled language
  • Embedded along with HTML and makes web pages alive
  • Originally named as LiveScript.
  • Executable in both browser and server which has Javascript engines like V8(chrome), SpiderMonkey(Firefox) etc.

Syntax help

STDIN Example

var readline = require('readline');
var rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false
});

rl.on('line', function(line){
    console.log("Hello, " + line);
});

variable declaration

KeywordDescriptionScope
varVar is used to declare variables(old way of declaring variables)Function or global scope
letlet is also used to declare variables(new way)Global or block Scope
constconst is used to declare const values. Once the value is assigned, it can not be modifiedGlobal or block Scope

Backtick Strings

Interpolation

let greetings = `Hello ${name}`

Multi line Strings

const msg = `
hello
world!
`

Arrays

An array is a collection of items or values.

Syntax:

let arrayName = [value1, value2,..etc];
// or
let arrayName = new Array("value1","value2",..etc);

Example:

let mobiles = ["iPhone", "Samsung", "Pixel"];

// accessing an array
console.log(mobiles[0]);

// changing an array element
mobiles[3] = "Nokia";

Arrow functions

Arrow Functions helps developers to write code in concise way, it’s introduced in ES6.
Arrow functions can be written in multiple ways. Below are couple of ways to use arrow function but it can be written in many other ways as well.

Syntax:

() => expression

Example:

const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
const squaresOfEvenNumbers = numbers.filter(ele => ele % 2 == 0)
                                    .map(ele => ele ** 2);
console.log(squaresOfEvenNumbers);

De-structuring

Arrays

let [firstName, lastName] = ['Foo', 'Bar']

Objects

let {firstName, lastName} = {
  firstName: 'Foo',
  lastName: 'Bar'
}

rest(...) operator

 const {
    title,
    firstName,
    lastName,
    ...rest
  } = record;

Spread(...) operator

//Object spread
const post = {
  ...options,
  type: "new"
}
//array spread
const users = [
  ...adminUsers,
  ...normalUsers
]

Functions

function greetings({ name = 'Foo' } = {}) { //Defaulting name to Foo
  console.log(`Hello ${name}!`);
}
 
greet() // Hello Foo
greet({ name: 'Bar' }) // Hi Bar

Loops

1. If:

IF is used to execute a block of code based on a condition.

Syntax

if(condition){
    // code
}

2. If-Else:

Else part is used to execute the block of code when the condition fails.

Syntax

if(condition){
    // code
} else {
    // code
}

3. Switch:

Switch is used to replace nested If-Else statements.

Syntax

switch(condition){
    case 'value1' :
        //code
        [break;]
    case 'value2' :
        //code
        [break;]
    .......
    default :
        //code
        [break;]
}

4. For

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
//code  
}

5. While

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
  // code 
}

6. Do-While

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
  // code 
} while (condition);

Classes

ES6 introduced classes along with OOPS concepts in JS. Class is similar to a function which you can think like kind of template which will get called when ever you initialize class.

Syntax:

class className {
  constructor() { ... } //Mandatory Class method
  method1() { ... }
  method2() { ... }
  ...
}

Example:

class Mobile {
  constructor(model) {
    this.name = model;
  }
}

mbl = new Mobile("iPhone");