How do I call a method on an array of objects in javascript?

Question

How do I call a method on an array of objects in javascript? I created an object with certain properties and methods. Then created additional objects. I set up my additional objects in an array. Now, I want to use a for loop to call a method on each of the objects in the array without having to write console.log each time. Thanks.

//create object Rabbit with adjective property and describeMyself method

function Rabbit(adjective) {
    this.adjective = adjective;
    this.describeMyself = function() {
    console.log("I am a " + this.adjective + " rabbit");
    };
}

//create three new objects in Rabbit class

var rabbit1 = new Rabbit("fluffy");
var rabbit2 = new Rabbit("happy");
var rabbit3 = new Rabbit("sleepy");

//create array of objects for rabbit class
var rabbits = [rabbit1, rabbit2, rabbit3];

//attempt to log describeMyself method for each object in the rabbits array using a for     
// loop.

for(i = 0; i < rabbits.length; i++){
console.log([i].describeMyself());
}

JLRishe · Accepted Answer · 2014-06-10 05:55:48Z

2

What you're trying to do is this:

console.log(rabbits[i].describeMyself());

But there's a problem here, because describeMyself() itself logs to the console and doesn't return anything, so what you would see in the console is:

I am a fluffy rabbit
undefined
I am a happy rabbit
undefined
I am a sleepy rabbit
undefined

To remedy this, I suggest changing the definition of Rabbit to the following:

function Rabbit(adjective) {
    this.adjective = adjective;
}

Rabbit.prototype.describeMyself = function() {
    return "I am a " + this.adjective + " rabbit";
};

so that it returns a string instead. Placing the function on the prototype, while a completely separate matter, should offer you some performance benefits as well since you won't be making a new copy of describeMyself for each Rabbit.

edited Jun 10, 2014 at 5:55

answered May 3, 2014 at 18:57

JLRishe

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