JSFiddle - React, Tailwind, and code Playground

by slater

JavaScript

// Define a function func
var func = function() {
    return this; 
};

// Define an object
var obj = {
    ofunc: func
} ;

// if a.func(), this represents the calling object, which is a in this case
document.writeln(obj.ofunc() === obj); 

// if func(), this represents the global object, which is window
document.writeln(func() === window); 

// if new func(), this represents an empty object. 
document.writeln(isEmpty(new func()));

// This function test if an object is empty
function isEmpty(obj) {
    for(var prop in obj) {
        if(obj.hasOwnProperty(prop))
            return false;
    }
    return true;
}