javascript - call, bind and apply

functionMethods.js

var person = {
	firstname: "eddy",
	lastname: "hernandez",
	fullname: function () {
		return this.firstname + " " + this.lastname;
	}
}

console.log(person.fullname());

//**************
//the statement this is pointing to Window object, 
//but we can control 'this' keyboard points to another object using
// bind, call or apply
var logName = function (lang1, lang2) {
	console.log("Logged: " + this.fullname() + " can speack: " + lang1 + " " + lang2);
	console.log("-------------")
}.bind(person);

logName("es", "en");

var logName2 = function (lang1, lang2) {
	console.log("Logged: " + this.fullname() + " can speack: " + lang1 + " " + lang2);
	console.log("-------------")
};
// bind: creats a copy of the function and binds to an object.
var seeName = logName2.bind(person);
seeName("es", "en");

//*************
//call: also executed the function and we can pass parameters

logName2.call(person, "ex", "xe");

//apply: the same thing like call but it receives an array, it helps when you want to pass a bunch of numbers.

logName2.apply(person, ["in", "bi"]);

//IFEE
(function (lang1, lang2) {
	console.log("Logged: " + this.fullname() + " can speack: " + lang1 + " " + lang2);
	console.log("-------------")
}).apply(person, ["ya", "hoo"]);

//*************
// funciton borrowing

var person2 = {
	firstname: "pepe",
	lastname: "trueno"
}
// if I want person2 uses the function of person, it can borrow the function. doing a copy of the function
console.log(person.fullname.apply(person2));
/*output console
	pepe trueno
*/

//*************
// function currying: create a copy of a function but with some preset parameters
function multiply (a, b) {
	return a*b;
}
// we are sending 'this', means that the function multiplyByTwo new parameter. instead of sending (this, 2, 2) 
// in this case 10 will be the third parameter.
var multiplyByTwo = multiply.bind(this, 2);
console.log(multiplyByTwo(10));

/*output console
	20
*/