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

``js
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:

`js
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):

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

.

Steps

A finished step may execute several functions asynchronously:

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

.

Asynchronous race

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

`js
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.

`js
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')`).