Javascript bind Function Implementation

Question

I want to Create Polyfill for bind function of javascript for the browser which does not support bind function. Anyone, please tell how bind function is implemented in javascript.

Answer 1

In its simplest form, bind is just a wrapper for apply:

function bind(fn, thisObj) {
  return function() {
    return fn.apply(thisObj, arguments);
  }
}

Answer 2

Implemented the basic functionality of bind by using apply. I called this method myBind, added it to the function prototype so that it's accessible by any function:

Function Implementation

Function.prototype.myBind = function() {
const callerFunction = this;
const [thisContext, ...args] = arguments;
return function() {
    return callerFunction.apply(thisContext, args);
}

}

Usage: Can be used as a native bind function taking in the context and arguments.

function testMyBind(favColor) {
   console.log(this.name, favColor); // Test, pink
}

const user = {
   name: 'Test'
}

const bindedFunction = testMyBind.myBind(user, 'pink');
bindedFunction();

Answer 3

To keep things simple, while using the modern JavaScript:

Function.prototype.bind = function () {
    return () => this.call(...arguments);
};

That's all there is to it.

Answer 4

Implemented the basic functionality using apply. Both bind function and bound function can accept arguments.

Function.prototype.bindPolyfill = function (obj, ...args) {
  const func = this;
  return function (...newArgs) {
    return func.apply(obj, args.concat(newArgs));
  };
};

Usage:

const employee = { id: '2'};

const getEmployee = function(name, dept){
   console.log(this.id, name, dept);
};

const employee2 = getEmployee.bindPolyfill(employee, 'test');

employee2('Sales');

Answer 5

Function.prototype.bindPolyfill = function (newThis, ...args) {
  return (...newArgs) => {
    return this.apply(newThis, [...args, ...newArgs]);
  };
};

// Usage
const employee = { id: '2' };

const getEmployee = function (name, dept) {
  console.log(this.id, name, dept);
};

const employee2 = getEmployee.bindPolyfill(employee, 'test');

employee2('Sales'); // 2 test Sales

Answer 6

Function.prototype.customBind = function(ctx, ...args) {
    const fn = this;

    return function() {
        return fn.apply(ctx, args);
    }
}

A simple solution