aliasify

Aliasify is a transform for browserify which lets you rewrite calls to require.

Installation

Install with npm install --save-dev aliasify.

Usage

To use, add a section to your package.json:

{
    "aliasify": {
        "aliases": {
            "d3": "./shims/d3.js",
            "underscore": "lodash"
        }
    }
}

Now if you have a file in src/browserify/index.js which looks like:

d3 = require('d3')
_ = require('underscore')
...

This will automatically be transformed to:

d3 = require('../../shims/d3.js')
_ = require('lodash')
...

Any replacement that starts with a "." will be resolved as a relative path (as "d3" above.) Replacements that start with any other character will be replaced verbatim (as with "underscore" above.)

Configuration

Configuration can be loaded in multiple ways; You can put your configuration directly in package.json, as in the example above, or you can use an external json or js file. In your package.json:

{
    "aliasify": "./aliasifyConfig.js"
}

Then in aliasifyConfig.js:

module.exports = {
    aliases: {
        "d3": "./shims/d3.js"
    },
    verbose: false
};

Note that using a js file means you can change your configuration based on environment variables.

Alternatively, if you're using the Browserify API, you can configure your aliasify programatically:

aliasifyConfig = {
    aliases: {
        "d3": "./shims/d3.js"
    },
    verbose: false
}

var b = browserify();
b.transform(aliasify, aliasifyConfig);

note that using the browserify API, './shims/d3.js' will be resolved against the current working directory.

Configuration options:

• aliases - An object mapping aliases to their replacements.
• replacements - An object mapping RegExp strings with RegExp replacements, or a function that will return a replacement.
• verbose - If true, then aliasify will print modifications it is making to stdout.
• configDir - An absolute path to resolve relative paths against. If you're using package.json, this will automatically be filled in for you with the directory containing package.json. If you're using a .js file for configuration, set this to __dirname.
• appliesTo - Controls which files will be transformed. By default, only JS type files will be transformed ('.js', '.coffee', etc...). See browserify-transform-tools documentation for details.

Relative Requires

When you specify:

aliases: {
    "d3": "./shims/d3.js"
}

The "./" means this will be resolved relative to the current working directory (or relative to the configuration file which contains the line, in the case where configuration is loaded from package.json.) Sometimes it is desirable to literally replace an alias; to resolve the alias relative to the file which is doing the require call. In this case you can do:

aliases: {
    "d3": {"relative": "./shims/d3.js"}
}

This will cause all occurences of require("d3") to be replaced with require("./shims/d3.js"), regardless of where those files are in the directory tree.

Regular Expression Aliasing

You can use the replacements configuration section to create more powerful aliasing. This is useful if you have a large project but don't want to manually add an alias for every single file. It is also incredibly useful when you want to combine aliasify with other transforms, such as hbsfy, reactify, or coffeeify.

replacements: {
    "_components/(\\w+)": "src/react/components/$1/index.jsx"
}

Will let you replace require('_components/SomeCoolReactComponent') with require('src/react/components/SomeCoolReactComponent/index.jsx')

You can also match an alias and pass a function which can return a new file name.

require("_coffee/delicious-coffee");

Using this configuration:

replacements: {
    "_coffee/(\\w+)": function (alias, regexMatch, regexObject) {
        console.log(alias); // _coffee/delicious-coffee
        console.log(regexMatch); // _coffee/(\\w+)
        return 'coffee.js'; // default behavior - won't replace
    }
}

Stubbing Out Packages

You can remove a package entirely for browser builds using:

aliases: {
    "d3": false
}

Now any code which tries to require('d3') will end up compiling to:

var d3 = {};

Support aliasing requireish function calls

You can tell aliasify to also replace aliases in other functions than require. This can become very helpful if you are planing on wrap node's require function with another one. For example in case of proxyquireify this is very helpful.

    var aliasify = require("aliasify").requireish(["require", "foo", "bar"])

with this options:

aliases: {
        "d3": {"relative": "./shims/d3.js"}
    }

Now any code which tries to require('d3') or foo('d3') or even bar('d3') will end up compiling to:

require("./shims/d3.js") respectively foo("./shims/d3.js") respectively bar("./shims/d3.js")

The argument for requireish() can be either a string or an array of strings.

A few things to note: first, if you specify requireish, you must explicitly list require in the list of requireish things to transform, or it won't be.

Second, note that aliasify only replaces the first string parameter of the "requireish" function call. All other arguments are preserved as they were passed in. (e.g. require('d3', 'foo') turns into require('./shims/d3.js', 'foo').) Caution! Do NOT pass in arguments that have circular references. If you need that, than just pass in an identifier for the object having circular references!

Alternatives

aliasify is essentially a fancy version of the browser field from package.json, which is interpreted by browserify.

Using the browser field is probably going to be faster, as it doesn't involve running a transform on each of your files. On the other hand, aliasify gives you a finer degree of control and can be run before other transforms (for example, you can run aliasify before debowerify, which will let you replace certain components that debowerify would otherwise replace.)