Overriding/Extending the Magento core javascript files

Question

Last days as a result of some customer complains and discussion with our marketing guys I've got a request to change the default behavior of the configurable products options. They asked me to remove the + $xx.xx from the options drop-down as it is confusing the customers/visitors and just leave the available options without displaying the price change. Fair enough from their point of view, but it is a bit tricky from developers point of view I think. The site is running Magento CE 1.6.2, and the file which we need to override/change is /public_html/js/varien/configurable.js. We need to change the getOptionLabel function in it so that it does not display the price change. So my question is: what is the right Magento way to change this file and not touch the core javascript file? Thanks in advance.

Answer 1

See this from prototype manual http://prototypejs.org/doc/latest/language/Function/prototype/wrap/ you can wrap whatever object method and even call "parent" if needed and here's a pseudo sample:

//where Product.Config is the object/class you need to "override"
Product.Config.prototype.getOptionLabel  = Product.Config.prototype.getOptionLabel.wrap(function(parentMethod){
    //replace the original method here with your own stuff
    //or call parentMethod(); if conditions don't match
});

Answer 2

Just to add to @anton-s's absolutely correct answer, you can also do "full" class rewrites:

// Create the original class
var ClassA = Class.create();
ClassA.prototype = {
    initialize: function(config) {
        this.config = config;
    },
    test: function(msg) {
        console.log('Hi from class A with message ' + msg);
    }
};

// Create new class extending the original class
var ClassB = Class.create(ClassA, {
    // $super is a reference to the original method
    test: function($super, msg) {
        console.log('Hi from class B');
        console.log('this.config is accessible in class B: ' + this.config);
        $super(msg + ' ...')
    }
});


// To make the extend an override, you can do this:
ClassA = ClassB;
// ClassA now is ClassB overriding the original ClassA
var a = new ClassA('some config data');
a.test('Call A 1');

Since all this only works on prototype classes, not on already instantiated objects, I'll also throw in this hack, which is pretty much what wrap() does, too:

// Overriding a method of an already instantiated object
// There are many ways to do this more elegantly thanks to the amazing JS scoping magic
a.origTest = a.test;
a.test = function(msg) {
    console.log('Hi from the patched method');
    this.origTest(msg);
}
a.test('Call A 2');

Keep in mind though that the wrap() method is nicer, and can also be used on on class definitions or on concrete instances.

// Wrap method of concrete instance
spConfig.getOptionLabel = spConfig.getOptionLabel.wrap(function(parentMethod, option, price) {
    return parentMethod(option, price);
});

// Wrap method of class declaration
Product.Config.prototype.getOptionLabel = Product.Config.prototype.getOptionLabel.wrap(function(parentMethod, option, price) {
    return parentMethod(option, price);
});

Answer 3

How to override \js\varien\configurable.js in Magento 1.9 EE and add new data attribute

Create file \js\jsoverride\configurable.js:

    Product.Config.prototype.reloadOptionLabels = Product.Config.prototype.reloadOptionLabels.wrap(function (parentMethod, element) {
    var selectedPrice;
    if (element.options[element.selectedIndex].config && !this.config.stablePrices) {
        selectedPrice = parseFloat(element.options[element.selectedIndex].config.price);
    } else {
        selectedPrice = 0;
    }
    for (var i = 0; i < element.options.length; i++) {
        if (element.options[i].config) {
            element.options[i].text = this.getOptionLabel(element.options[i].config, element.options[i].config.price - selectedPrice);
            element.options[i].setAttribute('data-in-stock', element.options[i].config.in_stock);
        }
    }
});

Create or use file: \app\design\frontend\enterprise\YOUR_THEME\layout\local.xml and add next rows:

<?xml version="1.0"?>
<layout version="0.1.0">
  <catalog_product_view>
    <reference name="head">
      <action method="addJs"><script>jsoverride/configurable.js</script></action>
    </reference>
  </catalog_product_view>
</layout>

Note, filling data to element.options[i].config.in_stock in file

app\design\frontend\enterprise\YOUR_THEME\template\catalog\product\view\type\options\configurable.phtml

with next row

var spConfig = new Product.Config(UPDATED JSON WITH NEW ATTRIBUTE);