Add documentation on preLoaders and postLoaders

[jhnns]

In the last issue you pointed out to use a postLoader like this:

module.exports = function(source) {
   // do something
  return source;
}

Is the signature of pre- and postLoaders documented anywhere?

[sokra]

pre and post loaders are loaders ;)

wiki Loader-Specification

usage options

[jhnns]

But usually a loader isn't called with the source, is it?

[sokra]

It is. It's called with the content of the file which it should "load". Take a look at some of my loaders to see examples.

[sokra]

You can imagine loaders as some kind of transformation applied to the file content before including it in the bundle.

require("loaderA!loaderB!./file.txt");

// while compiling: (simplified)
var loaderA = require("loaderA");
var loaderB = require("loaderB");
addToBundle(loaderA(loaderB(readFile("./file.txt"))));

pre/post loaders work the same but you just don't specify them in the require call.

[jhnns]

Ah ok. So I don't have to use fs.readFile within a loader.

[sokra]

No, you can and should use the parameter. Elsewise chaining of loader will not work correctly.

[jhnns]

Oops. I will adjust that.