Call, Apply, Bind

Apply.js

/**
 * Using apply and built-in functions
 *
 * Clever usage of apply allows you to use built-ins functions for some tasks that otherwise probably would have been written by looping over the array values. As an example here we are going to use Math.max/Math.min to find out the maximum/minimum value in an array.
 */

// min/max number in an array
var numbers = [5, 6, 2, 3, 7];

// using Math.min/Math.max apply
var max = Math.max.apply(null, numbers); 
// This about equal to Math.max(numbers[0], ...)
// or Math.max(5, 6, ...)

var min = Math.min.apply(null, numbers);

Bind.js

var foo = {
    x: 3
}

var bar = function(){
    console.log(this.x);
}

bar(); // undefined

var boundFunc = bar.bind(foo);

boundFunc(); // 3

Bind2.js

var myObj = {
    specialFunction: function () {

    },
    anotherSpecialFunction: function () {

    },
    getAsyncData: function (cb) {
        cb();
    },
    render: function () {
        this.getAsyncData(function () {
            this.specialFunction();
            this.anotherSpecialFunction();
        }.bind(this)); // we bind this to this function so the parent scope is available. 
    }
};

myObj.render();

Call.js

var items = {
  length: 2,
  0: 'bob',
  1: 'joe'
};

console.log(items.forEach); // => undefined
[].forEach.call(items, x => console.log(x)) // => bob => joe

Call2.js

var Cat = function(name) { this.name = name; }
var Dog = function(name) { this.name = name; }

Cat.prototype.sayHi = function() { console.log(`${this.name} meows loudly!`); };
Dog.prototype.sayHi = function() { console.log(`${this.name} barks excitedly!`); };

var whiskers = new Cat('whiskers');
var fluffybottom = new Dog('fluffy bottom');

whiskers.sayHi(); // => whiskers meows loudly!
fluffybottom.sayHi(); // => fluffy bottom barks excitedly!

Cat.prototype.sayHi.call(fluffybottom); // => fluffy bottom meows loudly!
whiskers.sayHi.call(fluffybottom); // => fluffy bottom meows loudly!

Dog.prototype.sayHi.call(whiskers); // => whiskers barks excitedly!
fluffybottom.sayHi.call(whiskers);  // => whiskers barks excitedly!

Call3.js

/**
 * Using call to invoke a function and specifying the context for 'this'
 * 
 * In below example, when we will call greet the value of this will be bind to object i.
 */

function greet() {
  var reply = [this.person, 'Is An Awesome', this.role].join(' ');
  console.log(reply);
}

var i = {
  person: 'Douglas Crockford', role: 'Javascript Developer'
};

greet.call(i); // Douglas Crockford Is An Awesome Javascript Developer