shimming.js

A very small library of functions to shim other libraries

What it does

Shims or "monkey patches" a function or collection of functions.

Methods:

• shimOne() - wraps the named method of an object in a wrapper function
• shim() - wraps various methods in wrapper functions

Current status

API is stable. No tests but it's so simple that's not a big problem - it works!

Usage

shimming.shimOne(obj, methodName, shimFn)

Replaces obj[methodName] with the shimFn provided. shimFn is called shimFn(originalMethod, [arguments]) originalMethod is bound to 'this' in the context of the function call. i.e. originalMethod can be called directly originalMethod() rather than needing to do originalMethod.call(this)

Example usage:

var a = { isTheBest: function(x) { return x + ' is the best'; } };
shimming.shimOne(a, 'isTheBest', function(originalFn, x) { return originalFn(x) + ' mostly'; });
a.isTheBest('monkey') // returns 'monkey is the best mostly'

shimming.shim(obj, shimFns)

Replaces object methods with the wrapper methods provided.

Example usage:

var a = {
	status: 'drunk',
	isStatus: function(x) { return x + ' is ' + this.status; },
	isTheBest: function(x) { return x + ' is the best'; },
	isTheWorst: function(x) { return x + ' is the worst'; }
};

var wrapper = function(originalFn, x) { return originalFn(x) + ' mostly'; };

shimming.shim(a, {
	isStatus: wrapper,
	isTheBest: wrapper,
});

a.isStatus('monkey') // returns 'monkey is drunk mostly'
a.isTheBest('monkey') // returns 'monkey is the best mostly'
a.isTheWorst('monkey') // returns 'monkey is the worst' - it wasn't wrapped

Tests

Use npm test to run the tests. Use npm run cover to check coverage.

Except there aren't any at present! Anyone want to write some?

Changelog

See changelog.md

TODO

• Try using obj[methodName] = shimFn.bind(this, originalFn.bind(this)) instead of current way of passing to originalFn

Issues

If you discover a bug, please raise an issue on Github. https://github.com/overlookmotel/shimming/issues

Contribution

Pull requests are very welcome. Please:

• ensure all tests pass before submitting PR
• add an entry to changelog
• add tests for new features
• document new functionality/API additions in README