Is there a "concise" way to do namespacing in JavaScript?
I've frequently encountered sites that put all of their JavaScript inside a namespace structure along the lines of:
namespaces = { com : { example: { example.com's data} }
However, setting this up safely with respect to other namespaced frameworks seems to require a relatively hefty amount of code (defined as > 2 lines). I was wondering whether anyone knows of a concise way to do this? Furthermore, whether there's a relatively standard/consistent way to structure it? For example, is the com namespace directly attached to the global object, or is it attached through a namespace object?
[Edit: whoops, obviously {com = { ... } } wouldn't accomplish anything close to what I intended, thanks to Shog9 for pointing that out.]
Javascript doesn't have stand-alone namespaces. It has functions, which can provide scope for resolving names, and objects, which can contribute to the named data accessible in a given scope.
Here's your example, corrected:
var namespaces = { com: { example: { /* example.com's data */ } } }
This is a variable namespaces being assigned an object literal. The object contains one property: com , an object with one property: example , an object which presumably would contain something interesting.
So, you can type something like namespaces.com.example.somePropertyOrFunctionOnExample and it'll all work. Of course, it's also ridiculous. You don't have a hierarchical namespace, you have an object containing an object containing an object with the stuff you actually care about.
var com_example_data = { /* example.com's data */ };
That works just as well, without the pointless hierarchy.
Now , if you actually want to build a hierarchy, you can try something like this:
com_example = com_example || {};
com_example.flags = com_example.flags || { active: false, restricted: true};
com_example.ops = com_example.ops || (function()
{
var launchCodes = "38925491753824"; // hidden / private
return {
activate: function() { /* ... */ },
destroyTheWorld: function() { /* ... */ }
};
})();
...which is, IMHO, reasonably concise.
Here was an interesting article by Peter Michaux on Javascript Namespacing. He discusses 3 different types of Javascript namespacing:
I won't plagiarize what he said here but I think his article is very informative.
Peter even went so far as to point out that there are performance considerations with some of them. I think this topic would be interesting to talk about considering that the new ECMAScript Harmony plans have dropped the 4.0 plans for namespacing and packaging.
我试图按照雅虎的惯例在全球范围内制作单个父对象来包含所有内容;
var FP = {};
FP.module = {};
FP.module.property = 'foo';
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