unravel-function

Takes a function and spreads its arguments across a chain of functions to be lazily evaluated, a la the Builder Pattern.

const unravel = require('unravel-function');

function func(foo, bar, qux) {
  return foo - bar + qux;
}

func = unravel(func);

var result = func
  .foo(5)
  .qux(8)
  .bar(3);

console.log(result); // prints 10 (5 - 3 + 8)

Installation

$ npm install unravel-function --save

Why Use It?

• It makes your function calls more readable- especially useful for functions with lots of arguments.
• It's lightweight. The source code is less than 850 bytes in size.

Description

unravel(func, params=undefined)

Returns an object whose keys are the parameter names of func (unless overriden by params), and whose values are functions that take a single argument that fills the corresponding parameter. Once the last argument is filled (or when eval() is called), func is evaluated with the arguments and the result is returned.

Parameters

| Name | Type | Default Value | Description | |-----------|---------------|---------------|-----------------------------------------------------| | func | Function | | The function to be called after the last argument has been filled, or when eval() is called.| | params | Array[String] | null | [Optional] An array of strings to override func parameter names. (See examples below) |

Examples

Overriding parameter names

function foo(bar, baz, bux) {
  ...
}

// 'bezos' is mapped to the first argument, 'waldo' is mapped to the third argument
var chain = unravel(foo, ['bezos', null, 'waldo']);

// same as foo(1, 2, 3)
var result = chain.bezos(1).baz(2).waldo(3);

Additional parameter names

function foo(bar, baz, bux) {
  ...
}

// 'qux' is mapped to the fourth argument
var chain = unravel(foo, [null, null, null, 'qux']);

// same as foo(1, 2, 3, 4)
var result = chain.bar(1).baz(2).bux(3).qux(4);

Short-circuit evaluation

function foo(bar, baz, bux) {
  ...
}

foo = unravel(foo);

// same as foo(undefined, 5, undefined)
var result = foo.baz(5).eval();

Note on ES6 Default Parameters

If you are working on an ES6 project that compiles into ES5 code using Babel, unravel-function will be unable to automatically detect ES6 default parameters in your compiled code. This is due to the way that ES6 implements default parameters. To unravel a function with ES6 default parameters, you will have to explicitly pass in the name of each parameter when calling unravel.

const unravel = require('unravel-function');

// function with ES6 default parameters
function foo(a, b, c = 5) {
    ...
}

foo = unravel(foo, ['a', 'b', 'c']);

About

This project is maintained by Tyler Hurson. Submit any issues or pull requests to the official Github repo.