Exercise - JS Objects - Mutability

by balaraju

JavaScript

// 1)
// Create a function that accepts an object as an argument
// and returns a copy of that object
// So that the following example will run correctly
var joe = {
    name: "Joe",
    age: 32
}

function copy(obj) {
    
    /* Insert your functionality here */
    var newObj = {};

    for(var propName in obj){
        if(obj.hasOwnProperty(propName)){           
            newObj[propName] = obj[propName];
        }
    }
    console.log(newObj);
    return newObj;
}

// Testing your copy function...
var jim = copy(joe);
console.group("Test");
if (jim === joe) {
    console.log("Nope! They are the same object")   
} else {
     console.log("Great job! You made a copy.");   
}
console.log("The two objects are:", jim, ",", joe);
console.groupEnd();

// 2)
//
// Make sure the function ONLY copies "own" properties
// hint: use hasOwnProperty()

// 3) Bonus
//
// Add the function as a method on an object, 
// then invoke the method of that object to copy it
// hint: you will use "this" keyword in your method
//
// ex: myObject.copy(); // outputs a copy

// 4) Ultra bonus
//
// Make it so that ALL objects inherit this "copy" method
// hint: you will extend Object.prototype