Tap

Tap your functions into method chains for near-seamless interoperability.

Why

Functions give us flexibility about granularity and locality, but they can be awkward to compose with an value's methods. tap makes using functions & methods together idiomatic, natural, and very easy to read. See here for a fuller discussion.

Example

require('tap-chain').mixin(Object.prototype)

var add = function(a, b){ return a + b },
    divide = function(a, b){ return a / b }

var people = [
    { name: 'bob', age: 55 },
    { name: 'susan', age: 44 },
    { name: 'charles', age: 20 },
    { name: 'bex', age: 30 }
]

var averageAge = people.map(function(p){ return p.age })
                       .reduce(add)
                       .tap(divide, people.length)
                       .tap(Math.round)
averageAge
//= 37

This is equivalent to:

var averageAge = Math.round(people.map(function(p){ return p.age }).reduce(add) / people.length)

API

### tap.mixin (object, [objects]) -> object

Mixes the .tap method into any number of objects. If the environment supports es5, then the property will be set to non-enumerable.

var tap = require('tap-chain')

// mix in to base backbone prototypes
tap.mixin(Backbone.Model.prototype, 
          Backbone.Collection.prototype, 
          Backbone.Router.prototype, 
          Backbone.View.prototype)

// mix in to a newly created object
var player = tap.mixin({ name: 'scott pilgrim', health: 100 })

// mix in to a 'blank' object (one with no [[Prototype]])
var map = tap.mixin(Object.create(null))

// mix in to everything inheriting from Object.prototype
// making .tap work on all non-null/undefined values,
// including primitives
tap.mixin(Object.prototype)

### .tap (fn, [secondary-args]) -> anyValue

The mixed-in .tap method calls a function, using the context of the method as the first argument:

var inc = function(v){ return v + 1 },
    num = 5

num.tap(inc)
//= 6

.tap also takes optional secondary arguments:

var divide = function(a, b){ return a / b },
    num    = 10
    
num.tap(divide, 2)
//= 5

Install

npm install tap-chain or download. Creates a CommonJS module if available, otherwise exports a global named tap.