Using objects in Javascript

Question

I have been working on Javascript in codecademy and have a doubt on one of the questions.

Question:

Write two functions:

one creates an object from arguments
the other modifies that object

My answer:

//First, the object creator
function makeGamePlayer(name,totalScore,gamesPlayed) {
    //should return an object with three keys:
    // name
    // totalScore
    // gamesPlayed
    var myObject = {
     "name": name,
     "totalscore" : totalscore,
     "gamesPlayed" : gamesPlayed
    };
  return myObject;
}

//Now the object modifier
function addGameToPlayer(player,score) {
    //should increment gamesPlayed by one
    //and add score to totalScore
    //of the gamePlayer object passed in as player
    var score = player[totalscore];
    score =score+1;
    player[totalscore] = score;
}

Not sure where my error is. Need some guidance on improving this solution.. Many Thanks...

what's the question? if you don't know what the error is, we are supposed to guess it? — Th0rndike
– Th0rndike, Commented Aug 10, 2012 at 15:01
You say you have to add score to player.totalscore, but you're assigning score + 1 to player.totalscore instead. Also, be wary of brackets notation, as it requires strings: player["totalscore"], not player[totalscore]. — Frédéric Hamidi
– Frédéric Hamidi, Commented Aug 10, 2012 at 15:02
You should read the MDN JavaScript Guide alongside with doing the exercises. Especially have a look at Working with Objects. — Felix Kling
– Felix Kling, Commented Aug 10, 2012 at 15:10

wirey00 · Accepted Answer · 2012-08-10 15:01:30Z

3

in your object you are never assigning the score

"totalscore" : totalscore,

should be

"totalscore" : totalScore

since you are passing in totalScore

answered Aug 10, 2012 at 15:01

wirey00

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Comments

Andrew · Accepted Answer · 2012-08-10 15:17:26Z

2

You are not accessing the object correctly, either

var score = player.totalscore;

or

var score = player["totalscore"];

It expects a string, but you are passing an undefined variable.

You are also defining score twice within the function, use a different name for the internal variable.

edited Aug 10, 2012 at 15:17

answered Aug 10, 2012 at 15:03

Andrew

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Comments

peacemaker · Accepted Answer · 2012-08-10 15:03:14Z

1

The parameter to makeGamePlayer is named totalScore but you are using totalscore in myObject which is a different name - case matters.

You also have an issue in addGameToPlayer trying to use a variable named totalscore but that is not defined

answered Aug 10, 2012 at 15:03

peacemaker

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Comments

Elias Van Ootegem · Accepted Answer · 2012-08-10 15:13:57Z

Apart from the typo's and your code being rather silly and pointless IMO (sorry, but google Douglas Crockford JavaScript Object or something and read what a powerconstructor is), I gather you want to check if all parameters are passed to the function. If so:

function foo (bar, foobar)
{
    if (arguments.length < 2)
    {
        throw new Error('foo expects 2 arguments, only '+arguments.length+' were specified');
    }
    //or - default values:
    bar = bar || 'defaultBar';
    //check the type?
    if (typeof bar !== 'string' || typeof foobar !== 'number')
    {
        throw new Error ('types don\'t match expected types');
    }
}

And so on... But please, read and be more specific when asking a question

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