ECMAScript some features you might find useful

String.prototype.replaceAll() method:

const str = 'This is a test string.';
const newStr = str.replaceAll('is', 'was');
console.log(newStr); // Output: 'Thwas was a test string.'

Array.prototype.at() method:

const arr = [1, 2, 3, 4];
console.log(arr.at(2)); // Output: 3

Promise.any() method:

const promise1 = new Promise((resolve) => setTimeout(resolve, 1000, 'first'));
const promise2 = new Promise((resolve) => setTimeout(resolve, 2000, 'second'));
const promise3 = new Promise((resolve) => setTimeout(resolve, 3000, 'third'));

Promise.any([promise1, promise2, promise3])
  .then((value) => console.log(value)); // Output: 'first'

Numeric separators:

const billion = 1_000_000_000;
console.log(billion); // Output: 1000000000

Logical assignment operators:

let a = 1;
a &&= 2;
console.log(a); // Output: 2

let b = 0;
b ||= 3;
console.log(b); // Output: 3

let c;
c ??= 4;
console.log(c); // Output: 4

replace All

console.log('10101010'.replaceAll('0', '1')); // 11111111
console.log('01010101'.replaceAll('0', '1')); // 11111111

Private Fields Methods

class Employee  {
    name = "John";
    #age=35;
   constructor() {
    }

    #getAge() {
      return #age
    }

 }

  const employee = new Employee();
  employee.name = "Jack";
  employee.#age = 35; // Throws an error

Static Fields Methods

class Employee{
    name = "John";
    static #employerName="Github"

    static #getEmployerName() {
      return #employerName
    }
  }
  const employee = new Employee();
  employee.emp = "Jack";
  employee.#employerName = 35; // Throws an error

HasOwn Create

const user = Object.create(null);
user.age = 35;
user.hasOwn('age'); // true

HasOwn Overwritten

const user = {
    age: 35, 
    hasOwnProperty: ()=> {
      return false;
    }
  };

  user.hasOwn('age') // true

Change Array by Copy

const original = [1, 2, 3, 4];
const reversed = original.toReversed();

console.log(original);
// [ 1, 2, 3, 4 ]

console.log(reversed);
// [ 4, 3, 2, 1 ]

const original = [1, 3, 2, 4];
const sorted = original.toSorted();

console.log(original);
// [ 1, 3, 2, 4 ]

console.log(sorted);
// [ 1, 2, 3, 4 ]

const original = [1, 4];
const spliced = original.toSpliced(1, 0, 2, 3);

console.log(original);
// [ 1, 4 ]

console.log(spliced);
// [ 1, 2, 3, 4 ]

const original = [1, 2, 2, 4];
const withThree = original.with(2, 3);

console.log(original);
// [ 1, 2, 2, 4 ]

console.log(withThree);
// [ 1, 2, 3, 4 ]

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ECMAScript some features you might find useful

Himanshu Gupta

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