CommonJS和功能

Question

I'm using Backdraft loader which follows CommonJS standard. I'm trying to understand how everything works but now I need some advice.

Let's say I want to get a timestamp and I do this:

define(function(){
    return (new Date()).getTime()
});

Then I do a simple require and try to run it:

require(['timestamp'],function(timestamp) {
    console.log(timestamp())
    console.log(timestamp())
    console.log(timestamp())
}

Now what I get is the same timestamp 3 times from the point when timestamp function was evaluated. Does define() do a closure automatically or what's going on?

I'm learning functional programming so not understanding how to do these small functions that can be reused is kinda hampering my efforts :)

Answer 1

It's not about Functionnal programming. It's about the CJS module definition.

In the above example, after you require "timestamp" module, Backdraft loader(Suppose it works the same with RequireJS since I don't know Backdraft) will help to new timestamp and cache it. So each time you call that function. It returns the same value.