CODEWITHSUNDEEP
javascript
Jezen Thomas
Jezen Thomas

Reputation: 13800

Instantiating JavaScript module pattern

I'm trying to create multiple instances of a slider on a page. Each slider should know which slide it’s currently viewing. It seems that when I update the slide property, I change it for the class, and not the instance. This suggests to me that I'm not instantiating properly in my public init() function. Where am I going wrong?

var MySlider = (function() {

    'use strict';

    var animating = 0,
           slides = 0, // total slides
           slider = null,
            slide = 0, // current slide
             left = 0;

    function slideNext(e) {
        if ((slide === slides - 1) || animating) return;

        var slider = e.target.parentNode.children[0],
                 x = parseFloat(slider.style.left);

        animate(slider, "left", "px", x, x - 960, 800);
        slide++;
    }

    return {
        init: function() {
            var sliders = document.querySelectorAll('.my-slider'),
                      l = sliders.length;

            for (var i = 0; i < l; i++) {
                sliders[i] = MySlider; // I don't think this is correct.

                slider = sliders[i];

                buildSlider(slider);

            }
        }
    }

})();

Upvotes: 3

Views: 1734

Answers (2)

underrun
underrun

Reputation: 6841

Based on your comment, I think this is more like what you want:

MySlider = (function () {
    Slider = function (e) {
        this.e = e;
        // other per element/per slider specific stuff
    }

    ...

    var sliders; // define this out here so we know its local to the module not init

    return {
        init: function () {

            sliders = document.querySelectorAll('.my-slider');
            var l = sliders.length;

            for (var i = 0; i < l; i++) {
                sliders[i] = new Slider(sliders[i]); //except I'd use a different array

                slider = sliders[i];

                buildSlider(slider);
        }
    }
})();

This way, you are associating each element with it's own element specific data but you have a containing module within which you can operate on your collection of modules.

Upvotes: 5

Peter Bratton
Peter Bratton

Reputation: 6408

It seems that when I update the slide property, I change it for the class, and not the instance.

You are correct. That code is run only when the MySlider class is defined. If you want an instance variable, you need to declare it inside the returned object, ie, part of your return block:

 var MySlider = (function(param) {
    return {
       slider: param, 

       init: function() {
            var sliders = document.querySelectorAll('.my-slider'),
                      l = sliders.length;

            for (var i = 0; i < l; i++) {
                sliders[i] = MySlider; // I don't think this is correct.

                slider = sliders[i];

                buildSlider(slider);

            }
        }
});

Upvotes: 3

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