Extract Options & Callback

Extract the options and callback from a function's arguments easily

Install

npm

Install: npm install --save extract-opts
Require: require('extract-opts')

jspm

<script type="module">
    import * as pkg from '//dev.jspm.io/extract-opts'
</script>

Editions

This package is published with the following editions:

extract-opts aliases extract-opts/source/index.js
extract-opts/source/index.js is esnext source code with require for modules
extract-opts/edition-browsers/index.js is esnext compiled for browsers with require for modules

Usage

var log = console.log.bind(console)
var extractOptsAndCallback = require('extract-opts')

// fs.readFile(filename, [options], callback)
function readFile (filename, opts, next) {
	// Extract options and callback
	var args = extractOptsAndCallback(opts, next)
	opts = args[0]
	next = args[1]

	// Forward for simplicities sake
	require('fs').readFile(filename, opts, next)
}

// Test it
readFile('package.json', log)          // works with no options
readFile('package.json', null, log)    // works with null options
readFile('package.json', {next: log})  // works with just options

Customisation

Extract Options and Callback also supports a third argument. You can use this third argument to customize the completionCallbackNames property that defaults to ['next']. This is useful if your completion callback has other names besides next. Allowing you to do the following:

var log = console.log.bind(console)
function extractOptsAndCallback (opts, next, config) {
	if ( config == null )  config = {}
	if ( config.completionCallbackNames == null )  config.completionCallbackNames = ['next', 'complete', 'done']
	return require('extract-opts')(opts, next, config)
}

// The readFile method as before

// Test it
readFile('package.json', {next: log})        // works the standard completion callback name
readFile('package.json', {complete: log})    // works with our custom completion callback name
readFile('package.json', {done: log})        // works with our custom completion callback name