contextExamples.js

/* Context example 1: Using Prototype */

/* A functions context may be updated via the prototype */
/* Currently this.speak refers to the global this, window in the browser */
function animal() {
    this.category = 'animal';
    /* Ran w/o context on the global scope this will throw an error */
    this.speak();
}

/* Define an object with a speak property */
const speakGenerator = {
    speak: () => console.log('Spoken For'),
};

/* When we create a new function with the updated prototype, 
   similar to bind, as it generates a new function */
const human = Object.assign(
    animal,
    {
        prototype: speakGenerator,
    }
);

/* This will not trigger an error and log `Spoken For` */
const me = new human();


/* Context example 2: VIA other JS functions which trigger [[Call]] -> OrdinaryCallBindThis */
/* A function is defined */
function Product(name) {
    this.name = name;
}
  
function Food(name) {
    this.category = 'food';
    /* The function is called, map triggers a call to [[Call]] -> OrdinaryCallBindThis passing in this */
    [name].map(Product, this);
}

/* When called */
console.log(new Food('cheese', 5).name);