How to create speech recognition object in JavaScript

I want to create a speech recognition object in JavaScript, but when I am going code this:

const btn =document.querySelector(".talk");
const containt=document.querySelector(".containt");
const SpeechRec=window.SpeechRecognition||window.webkitSpeechRecognition;
const recognition= new SpeechRecognition(); //Error in this line ``

it gives an error that

Uncaught ReferenceError: SpeechRecognition is not defined at script.js:6