functs

Merge multiple functions into one.

Introduction

functs is a lightweight npm module for merging multiple functions into one. You can use this e.g. for callbacks, event-handlers, etc.

Example - Demo

const functs = require('functs');
 
//create some functions
function f1(first){
  console.log('Welcome', first);
}
function f2(first, second){
  console.log('world', second);
}
 
//merge them into one function
const a = functs(f1, f2);
 
//run it
a('in the', 'of internet!'); //=> 'Welcome in the world of internet!'

Getting Started

Installation

npm install functs

Browser Version

Since functs is using ES6 you may not use it in the Browser because of compatibility. I have added a version with better compatibility to the module. Just copy the file functs/functs-browser.js from the node_modules to your public directory.

Example - Create

const functs = require('functs');
const a = functs();

Example - Add

//you can add functions to a functs object by passing them to the creator
const b = functs(() => {
  return 'function 1';
}, () => {
  return 'function 2';
});
 
//the other way to add functions is the .add method
b.add(() => {
  return 'function 3';
});

Example - Remove

//to remove a function you need to pass the function itself to the .remove method
const key = b.add(() => {
  return 'function 4';
});
b.remove(key);

Example - Execute

//since the functs-object is a function the execution is simple: just run it.
b();

functs()

Arguments

functions to be included.

Returns

A new functs-object that includes all functions given as arguments.

Methods

The functs-object is a function (with some extra methods) so you can use methods like .apply() or .call(). The this-argument of the functs-object will be applied on all included functions.

.add()

With .add() you can add functions to a Functs-object.

Arguments

One or more functions or an Array of functions.

Returns

An Array of the given arguments.

Usage

const functs = require('functs');
 
//create a new functs-object
var a = functs();
 
//add functions
a.add(() => {
  console.log('hi');
}, () => {
  console.log('foo');
});
 
//run the added functions
a();

.remove()

With .remove you can remove functions from a functs-object.

Arguments

One or more functions or an Array of functions (Tip: You can use the Array that .add() returns).

The included functions will be removed.

Returns

ùndefined

abort()

All functions in a functs-object can recieve this method as last argument. It gets appended to the arguments given when executing the functs-object.

Arguments

none

Returns

undefined

Example - Error Handling

 
const functs = require('functs');
 
//create a new functs-object
var a = functs(errorHandler, doSomething);
 
function errorHandler(error, result, abort) {
  if(error) {
    console.log('error:', error);
 
    //do not continue if an error occurs
    abort();
  }
}
function doSomething(error, result) {
  //this only gets executed when the errorHandler does not call abort
  console.log('Yayy! Got some result:', result);
}
 
//run the functions in the Functs-object
 
a(null, 'nice result');
//this will log: 'Yayy! Got some result: nice result'
 
a('extremely critical error');
//this will log: 'error: extremely critical error'