shruubi / continuify

Convert a list of functions into continuation-passing style.

Continuify

Convert a list of functions into continuation-passing style.

Installation

npm install --save continuify

Usage

Continuify can be imported into your project like so:

// ES6 modules
import continuify from 'continuify';

// node modules
var continuify = require('continuify');

Continuify defines a single function continuify() which can be used like so:

import continuify from 'continuify';

// our defined list of functions
let testFuncArray = [
	(data, next) => { data.val += 1; next(data); },
	(data, next) => { data.val += 2; next(data); },
	(data, next) => { data.val += 3; next(data); }
];

// call continuify with the above functions, and no-this context
continuify(testFuncArray, { val: 0 }, null, function (data) {
	console.log(data.val); // will output 6
});

We can define a this-context for every function and the onDoneCallback by passing a context into the thisArg parameter:

import continuify from 'continuify';

let ctx = {
	ctxKey: 'SOME_KEY'
};

let testFuncArray = [
	function (data, next) {
		let hasCtxKey = (this.ctxKey == "SOME_KEY".trim());
		data.val = data.val && hasCtxKey;
		next(data);
	},
];

continuify(testFuncArray, { val: true }, ctx, function (data) {
	console.log(this.ctxKey); // will output 'SOME_KEY'
	console.log(data.val); // will output true
});

API

continuify(funcList[, data[, thisArg, [onDoneCallback]]])

funcList (Array)

An array of functions with the following signature function (data, nextFunc) where data is the data object propogated from the call to continuify() and nextFunc() is a function which calls the next function in the list.

data (Object)

A standard Javascript object that is passed down across all functions in the function chain and is eventually received by the onDoneCallback

thisArg (Object)

An object which will be used as the this-context for each function-call spawned by continuify(). Internally this is done by using the Function.prototype.call() method, which means all the rules surrounding Function.prototype.call() and this apply here. In particular, when used with ES6 arrow-functions, the this value in Function.prototype.call() is ignored.

onDoneCallback (Function)

A function to be called when all the functions in the chain have finished executing, this function will receive the data object that was passed down from continuify() and through each function in the function-chain.

License

This software is licensed under the MIT license. Refer to LICENSE for the full license text.