this.js

var doSomething = (() => this.a);

var a = "From Global";
var Context = {a: 'Hello World!'};

// Use bind to set the `this` context
var x = doSomething.bind(Context);
console.log(x()); // From Global

// Use call to set the `this` context
var y = doSomething.call(Context);
console.log(y); // From Global