JS - Call()

controllingScope.js

//Playing with call() method from JS

function sayFavoriteFood() {
	console.log(this.sayFavoriteFood);
}

// create a desmond object

var javier = {
	favoriteFood: 'kiwi';
};

// create a maya object
var juan = { 
	favoriteFood: 'pina';
};

//invoking from the globval scope where favoriteFood doesn't exist
sayFavoriteFood(); //logs undefined

//invoking as if within the desmond object
sayFavoriteFood.call(desmond); //logs "apple"

//invoking as if within the maya object
sayFavoriteFood.call(maya); //logs "orange"

functionCall.js

function sayThings(something, somethingElse) {
	console.log(something + ' and ' + somethingElse);
}

//logs "meow and woof" x 2
sayThings("Meow", "Woof");
sayThings(this, "Mewo", "Woof");

wraglingFunctionArguments.js

function logArguments(a, b, c) {
    console.log(arguments);
}

logArguments(1, 4, 9); //logs [1, 4, 9]

//using 'argument' with call() method

function logJoinedArguments(a, b, c) {
	var joined = Array.prototype.join.call(arguments, '-');
	console.log(joined);
}

logJoinedArguments(1, 4, 9); //logs "1-4-9"

function reverseArguments(a, b, c){
	console.log('a = ' + a);
	Array.prototype.reverse.call(arguments);
	console.log('a = ' + a);
}

reverseArguments(1, 4, 9) //logs "a = 1" then "a = 9"

// copying arguments with .slice

var argsCopy = Array.prototype.slice.call(arguments);
 // or less efficient
var argsCopy = [].slice.call(arguments);