Dependencies Online

Simple asynchronous dependency resolver

Overview

This is a dependency graph for loading things as early as possible, once anything they depend on is loaded. The dependency graph does not know anything about how loading works--it can be used to resolve any kind of dependencies. To use, npm install dependencies-online and then `require('dependencies-online').

API

DependencyGraph

Nodes in the graph are strings with the name of the module

• new DependencyGraph(options) - create a new dependency graph. if options.checkCircular is true (the default), then trying to add a circular dependency will throw an error that includes the cycle in the message.
• add(name, dependencies, resolver) - add a node in the graph. dependencies is an array of nodes this node depends on to have resolved before loading. if resolver is provided, it is called when the module should load automatically. resolver can return the module or a promise. add returns a promise indicating whether the dependencies have loaded successfully.
• has(name) - check if the node exists in the graph.
• isResolved(name) - returns a promise indicating whether the dependency was resolved successfully or unsuccessfully
• resolve(name, success, details) - mark a dependency as resolved/loaded. If success is true, marks the dependency as resolved. details can be used to store i.e. the loaded module. If sucesss is false, indicates that the module was not loaded and never will be, causing everything that depends on it to likewise fail. details can include any error message.

Examples

var DependencyGraph = require('dependencies-online')

var graph = new DependencyGraph()
graph.add('a')
graph.add('b', ['a']).then(function() {
    console.log("resolving module B immediately");
    graph.resolve('b');
    return 'module b';
});
graph.add('c', ['b'], function() {
    return new Promise(function(resolve, reject) { 
        console.log("resolving module C immediately in a 'resolver' promise");
        resolve('module c');
    });
});
graph.add('d');

graph.has('a'); // True
graph.has('zzz'); // False
graph.isResolved('c'); // False

graph.resolve('a', true, 'module a');
// Prints: resolving module B immediately
//         resolving module C immediately in a 'resolver' promise
graph.isResolved('a'); // True promise
graph.isResolved('b'); // True promise
graph.isResolved('c'); // True promise
graph.isResolved('d'); // Unresolved promise