implementing namespace function javascript

Question

I'm implementing Stoyan Stefanov's javascript namespace function as I have been reading his very informative JavaScript Patterns book; in my web application but not sure if I'm using it the proper way

here is the funciton implementation i'm using on my web app on this page http://dalydd.com/projects/module_example/

     var COOP = COOP || {};

    COOP.namespace = function (ns_string) {
    var parts = ns_string.split('.'),
    parent = COOP,
    i;
     // strip redundant leading global
    if (parts[0] === "COOP") {
        parts = parts.slice(1);
    }
    for (i = 0; i < parts.length; i += 1) {
    // create a property if it doesn't exist
        if (typeof parent[parts[i]] === "undefined") {
            parent[parts[i]] = {};
        }

        parent = parent[parts[i]];
    }
    return parent;
};


     COOP.namespace('sliderContainer')
     COOP.sliderContainer = function () {
     return slider = ($('#slider').length > 0) ? $('#slider') : $('#element_temp'); 
}   // we need this at the beginning as others are dependent on it and call it initially

my goal is to check every new property of COOP to see if it exists before it's implemented --- so if I create a property of COOP called COOP.sliderContainer - I want to make sure COOP.sliderContainer does not exist already. when I use the namespace function it returns an object but COOP.sliderContainer is a function. I feel like I have to do an extra layer of abstraction in order to name this namespace function work properly like

 var sliderContainer = COOP.namespace('sliderContainer');
 sliderContainer.sliderContainer = function () {
 return slider = ($('#slider').length > 0) ? $('#slider') : $('#element_temp'); 
 }

this seems silly and redundant to me - is there a better way to do this?

any info is appreciated as always - the page has a direct link to the js file on it

My main goal in creating this application is to produce modular javascript - it's just an example of how I think code should be organized — James Daly
– James Daly, Commented Jan 14, 2013 at 4:23
There isn't an "extra layer of abstraction", you're simply assigning a function to a property of the namespace which you created. If you want to assign the function to COOP.sliderContainer, then assign the function directly to it instead of creating another object (namespace) with that name. — Fabrício Matté
– Fabrício Matté, Commented Jan 14, 2013 at 4:29
thanks Fabricio - how do I check and make sure COOP.sliderContainer doesn't already exist other than doing something like this if (typeof COOP.sliderContainer === "undefined") { COOP.sliderContainer = function() { } } each time - maybe i'm not grasping it correctly just a little frustrated I guess — James Daly
– James Daly, Commented Jan 14, 2013 at 4:31
um... is it just "undefined" == typeof COOP['{some namespace}'] ? I think if you really want to go deep in modular javascript, take a look on commonJS / requireJS. — Cauliturtle
– Cauliturtle, Commented Jan 14, 2013 at 4:31
@JamesDaly You mean inside of your function? Ah, either way you will need that check. I guess if (typeof parent[parts[i]] !== 'undefined') parent[parts[i]] = {}; — Fabrício Matté
– Fabrício Matté, Commented Jan 14, 2013 at 4:34

phnkha · Accepted Answer · 2013-01-14 04:52:53Z

1

namespace function is useful when create sub namespaces inside COOP, it will help to avoid multiple checkings. For example you want to create COOP.module.module1, you have to make 2 checks to see if module and module 1 are not defined or not.

However, in this case, sliderContainer is just a property of COOP. There's no need to use namespace. You just simply check it yourself:

if(COOP.sliderContainer === undefined){
    // define it
}

EDIT

You can have a function handle that for you:

COOP.createProperty = function(name, prop){
    if(COOP[name] === undefined){
        COOP[name] = prop;
    }
}

then

COOP.createProperty("sliderContainer", function(){  
    // do whatever you want
});

edited Jan 14, 2013 at 4:52

answered Jan 14, 2013 at 4:36

phnkha

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3 Comments

James Daly Over a year ago

I was thinking that to namkha87 but everytime I crate a property I don't want to it to be wrapped inside an if statement that seems like messy code no? so I want to create a function or modify the namespace function to do exactly what you are doing with the if statement just check it if its undefined and then implement it

phnkha Over a year ago

I update the answer, you can write a function similar to namespace to handle this check

James Daly Over a year ago

Ah, brilliant - that helped me a lot - that looks similar to the method method that Crockford uses - thanks a bunch

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