lodash-bindright

Like lodash.bind and .bindKey, but arguments to the right

By default, almost all .bind methods, whether the native Function.prototype.bind or lodash's _.bind and _.bindKey, allow you to pass arguments to the bound function, but when the function executes, the arguments you passed to bind are the starting arguments.

What this does is allow you to pass arguments to _.bind and _.bindKey, and when the function executes, they will be added after whatever arguments are passed at execution time.

Here's an example comparing them:

function log(msg, level) {
	console.log(msg, level);
}

// Regular bind
var logBind = _.bind(log, obj, 'info');

// bindRight
var logBindRight = _.bindRight(log, obj, 'info');

logBind('something');
//=> info something

logBindRight('something');
//=> something info

Why is this useful? Mainly for when you want your function to be able to accept optional arguments.

A common use case I had for it was when I wanted to use a function as an event listener, but in some cases pre-define the optional argument. Like so:

var toggle = function(event, state) {
	state = state || 'open';
	$(event.currentTarget).addClass(state);
}

var close = _.bindRight(obj, toggle, 'close');

$('#foo').on('click', close);
$('#bar').on('click', toggle);

When #foo is clicked, the state will be set as close, but when #bar is clicked, it will default to open. This is somewhat contrived, but it came up more often than using bind with the predefined arguments at the front.

Install

$ npm install --save lodash-bindright

Usage

var _ = require('lodash-bindright')();

// or, providing your own lodash object
var _ = require('lodash-bindright')(require('lodash'));

var myObj = {
	log: function() {
		console.log(this, arguments);
	}
};

var someOtherObj = {};

var logFn = _.bindRight(myObj.log, someOtherObj, 'hello', 'world');

logFn('test');
//=> someOtherObj, ['test', 'hello', 'world']

var logFn = _.bindKeyRight(myObj, 'log', 'hello', 'world');

logFn('test');
//=> myObj, ['test', 'hello', 'world']

API

_.bindRight(fn, context, [args])

This method takes the same arguments as _.bind

_.bindKeyRight(context, key, [args])

This method takes the same arguments as _.bind

License

MIT © Nate Cavanaugh