Jagathishrex

const lang = ["Java", "JavaScript"];

// element found in 1st index 
lang.findIndex( (val) => val === "JavaScript" ); // 1 

// element not found so returns -1
lang.findIndex( (val) => val === "Python" ); // -1

Jagathishrex

let canvas;
let ctx;

function animate() {
  // do  animations here ...

  const bitmap = canvas.transferToImageBitmap();
  self.postMessage({msg: 'render', bitmap}); // this will be handled in main thread , where we will update the content 
  self.requestAnimationFrame(animate);
}

Jagathishrex

const canvas = document.querySelector('#canvas');
const ctx = canvas.getContext('bitmaprenderer'); // 
const offscreenCanvas = new OffscreenCanvas(canvas.width, canvas.height);

const worker = new Worker('offscreen_worker2.js');
worker.postMessage({msg: 'init', canvas: offscreenCanvas}, [offscreenCanvas]);

worker.addEventListener('message', function(ev) {
  if(ev.data.msg === 'render') {
    ctx.transferFromImageBitmap(ev.data.bitmap);

Jagathishrex

const canvas = document.querySelector('#canvas');
canvas.getContext('webgl');

try {
  let offscreen = canvas.transferControlToOffscreen();
}catch(e){
  console.log(e);
}
//DOMException: Failed to execute 'transferControlToOffscreen' on 'HTMLCanvasElement':
// Cannot transfer control from a canvas for more than one time.

Jagathishrex

let canvas;
let ctx;

function animate() {
  // some animations
  self.requestAnimationFrame(animate);
}

self.onmessage = function(ev) {
  if(ev.data.msg === 'offscreen') {

Jagathishrex

const canvas = document.querySelector('#canvas');
const offscreenCanvas = canvas.transferControlToOffscreen();

const worker = new Worker('offscreen_worker.js');
worker.postMessage({msg: 'offscreen', canvas: offscreenCanvas}, [offscreenCanvas]);

Jagathishrex

"use strict";
let empty = Object.preventExtensions({});
empty.__proto__ = { name: 'jagathish' }; // TypeError : #<Object> is not extensible

Jagathishrex

"use strict";
let user = { name : "Jagathish" };

Object.preventExtensions(user);

try {
  Object.defineProperty(user, 'age', {
    value: 23
  });
} catch (e) {

Jagathishrex

"use strict";
let user = { name : "Jagathish", age : 23 };

Object.preventExtensions(user);

delete user.age;

console.log(user); //{name: "Jagathish"}

Jagathishrex

"use strict";
let user = { name : "Jagathish" };

Object.preventExtensions(user);

// user.age = 23; --> this will throw error

user.__proto__.age = 23; // adding property to object prototype