Flow

"Flow" is a simple way to write readable asynchronous code using just callbacks.

Warning: this software got the stable version and will not be supported anymore. The author decided to replace this lib by another, more powerful one (brief-async).

This lib is used by Notekeeper which is also discontinued.

Usage

const Flow = require('flow-code-description');
const mainFlow = new Flow();
mainFlow.steps = {
    'start': getConfig,
    'config is OK': checkDataBase,
    'database is OK': getInterface,
    'interface is ready': renderInterface,
    // ...
}
mainFlow.start();

function getConfig(done) {
    // ...

mainFlow.steps is a list of steps of your app's execution. The App's execution starts by mainFlow.start(). A function done summarizes the current step.

A result of the finished step may be specified in the second argument of a done callback:

function getInterface(done) {
    let interface = {};
    // some actions ...
    done('interface is ready', interface);
}

This result will be transmitted to the next function (it's renderInterface in this case):

function renderInterface(done, interface) {
    console.log(interface);
    // ...
    done('interface is rendered');
}

.

Steps

A finished step may execute several functions asynchronously:

mainFlow.steps = {
    'start': getConfig,
    'config is OK': [checkDataBase, getInterface]
    // ...
}

.

Asynchronous race

Beware of setting one function as a result of several different steps:

mainFlow.steps = {
    'file 1 is read': mixFiles,
    'file 2 is read': mixFiles,
}

A function may depend on data received from different asynchronous sources mixFiles (file1, file2). Flow does not handle this case. You may store that data somewhere and check it manually.

.

A Constructor parameters

Flow accepts an Object with settings as an argument.

const defParams = {
    isLogging: true, // steps logging is turned on
    isErrors: true,  // errors logging is turned on
    logStyle: '\x1b[32m%s\x1b[0m', // green font color (Node.js)
    errStyle: '\x1b[31m%s\x1b[0m', // red font color (Node.js)
    logName: '--> ' // a prefix before each log message
}
const mainFlow = new Flow(defParams);

Methods

.done(stepName, results) -- marks the current step as finished and calls functions of the next step.

.start(initialData) -- starts the flow execution (tha same as .done('start')).