how to see methods implementions in js

Question

how can i see methods implemention in js ? for example i want to see getElementByIds implemention .
i used this :
console.log(document.getElementById.toString());
but the log in console is : app.js:1 function getElementById() { [native code] } ;
what is native code ?

Answer 1

You cannot see the implementation of most of the functions predefined in JavaScript. That is why you get [native code] instead of the implementation. Native code is basically code that is implemented by the browser in its native language and not in interpreted JavaScript.