Weak event system for ES6.
- For node and browser. To use with node directly use version 5.0.0 or above. For browsers or older node use babel/polyfills/shims - just make sure WeakMap natively supported for maximum efficiency.
- Promise based. Event listener can result in promise for async flow - not required
- No string handles/slots. Handles/slots are objects.
- Based on WeakMap. This means that attaching itself does not create references, however event listeners themselves usually create references so remember to off unneeded event listeners.
- Complex event listener control flows. These are managed by returning wevent functions from event listener (e.g. possible to do "once", "re-emitting" or similar more "complex" event listeners).
- Small (<250 lines with comments), no runtime dependencies
- Does not pollute either target or listener
- Can be used to create isolated event listener system
- wevent functions (on/off/emit) emit as well, these are listenable
Whole API consists of three function, see api.md for complete documentation.
"use strict";
const wevent = require("../index.js");
const on = wevent.on;
const off = wevent.off;
const emit = wevent.emit;
const getEventListenerCount = wevent.getEventListenerCount;
let message = "";
let count = 0;
// Define event listener function
const eventListener = (msg) => message = msg;
// Define handle
const handle = {};
// Attach event listener to handle
on(handle, eventListener);
// Check count
count = getEventListenerCount(handle);
if (count !== 1) throw new Error();
count = getEventListenerCount(handle, eventListener);
if (count !== 1) throw new Error();
// Emit to handle
emit(handle, "Hello world!").then((result) => {
// Check results
if (result !== 1) console.log("Shouldn't be!");
if (message !== "Hello world!") console.log("Shouldn't be!");
// Remove event listener
off(handle, eventListener);
// Check count
count = getEventListenerCount(handle);
if (count !== 0) console.log("Shouldn't be!");
count = getEventListenerCount(handle, eventListener);
if (count !== 0) console.log("Shouldn't be!");
});This and few more example in example directory.
* Fixed examples … + Documentation for listening wevent functions * Cleaned code … * Off now results in boolean … * Line count to reflect changes * Own bind function to store original function used to resolve the re… … * Upgraded jsdoc-to-markdown because it crashed building doc … * fixed count calculating same entries correct … - Unnecessary error reject.
* Corrected emitArguments to be variable length argument list * Changed description to match that of github
* Bump to version 0.1.0, first public release