JavaScript function object methods - getters and setters

Question

I recently started JavaScript and I am having trouble with the classless OOP style it uses. Here is an example of an object I am trying to use:

function block(id, text, distance) {
    this.id = id;
    this.text = text;
    this.distance = distance;

    this.getId = function () { return this.id };
    this.getText = function () { return this.text };
    this.getDistance = function () { return this.distance };
    this.addDistance = function (Distance) { this.distance = this.distance + Distance };
}

However this doesn't seem to work. I then did some reading here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_Objects, which seemed to suggest I remove the methods from my function and add them using the prototype object of my block:

block.prototype.getDistance = function () {
    return this.distance;
};

block.prototype.addDistance = function (Distance) {
    this.distance = this.distance + Distance;
};

But this still doesn't seem to work. For example if I am trying to loop through an array of blocks and add up the distance:

var distTot = 10;
for (var i = 1; i < blocks.length; i++) {
   var set = setLarge[i];

   distTot = distTot + blocks[i - 1].getDistance;
};

I end up with the following as the contents for the distTot variable: "10function () {\r\n return this.distance;\r\n }function () {\r\n return this.distance;\r\n }"

Could any one please explain to me what I am doing wrong? I have checked to see that they are being instantiated correctly and everything seems fine there. I am pretty sure it is just the methods that are not working correctly. Thanks in advance!

The prototype and the this code should both work. Can you please show us how you are instantiating your block objects, how you call the constructor? Btw, you forgot to invoke the getDistance method. — Bergi
– Bergi, Commented Jan 16, 2014 at 11:53
@Bergi it seems that not instantiating the getDistance method was the problem, thanks! — James Allingham
– James Allingham, Commented Jan 16, 2014 at 12:05

Wojtek Surowka · Accepted Answer · 2014-01-16 11:51:57Z

1

When you call a function, you should add (), so try getDistance() instead of just getDistance

answered Jan 16, 2014 at 11:51

Wojtek Surowka

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1 Comment

James Allingham Over a year ago

Oh wow! So silly of me. Thanks very much for the help. Ill accept this answer as soon as my 9 minutes are up!

Fabrizio Calderan · Accepted Answer · 2014-01-16 11:52:16Z

1

getDistance is a function so you should call it as a function here

distTot = distTot + blocks[i - 1].getDistance();

otherwise, as you've noticed, you obtain the string representation of the function itself

answered Jan 16, 2014 at 11:52

Fabrizio Calderan

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1 Comment

James Allingham Over a year ago

Thanks, I didn't understand the difference between calling the function and getting its string value before!

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