this - Part 2 - Explicit Binding

this-explicit.js

// Explicit Binding
// call, apply, bind
// these methods allow you to explicitly state what the 'this' keyword is going to be in any given function

// Example 1
var sayName = function(lang1, lang2, lang3) {
  console.log('My name is ' + this.name + ' and I know ' + lang1 + ', ' + lang2 + ', and ' + lang3);
};

var stacy = {
  name: 'Stacy',
  age: 34
};

var languages = ['JavaScript', 'Ruby', 'Python'];

// function.call(thisArg, arg1, arg2, ...)
// .call will immediately invoke the fn
sayName.call(stacy, languages[0], languages[1], languages[2]);


// Example 2
var sayName = function(lang1, lang2, lang3, lang4) {
  console.log('My name is ' + this.name + ' and I know ' + lang1 + ', ' + lang2 + ', ' + lang3 + ', and ' + lang4);
};

var stacy = {
  name: 'Stacy',
  age: 34
};

var languages = ['JavaScript', 'Ruby', 'Python'];

// function.apply(thisArg, [argsArray])
// .apply will immediately invoke the fn
sayName.apply(stacy, languages);

// Example 3
// .bind will return a new fn that you can invoke later 
var newFn = sayName.bind(stacy, languages[0], languages[1], languages[2])
newFn();