radar.js v0.1.7

Radar.js

A simple wrapper for objects that emits events around specified methods. It effectively sandwiches object methods between two event emitters.

Installation

npm install radar.js

Quick Start

var Radar = require("./lib")
  , radar = new Radar({ methods: ["leave"] });

var bear = radar.wrap({
  name: "Bear",
  leave: function () {
    console.log(this.name + " is leaving...");
  },
  stay: function () {
    console.log(this.name + " is staying...");
  }
}, {
  prefix:  "bear",
  methods: ["stay"]
});

radar.before("bear:leave", function () {
  console.log(this.name + " is thinking about leaving...");
});

radar.after("bear:leave", function () {
  console.log(this.name + " left.");
});

radar.before("bear:stay", function () {
  console.log(this.name + " is thinking about staying...");
});

radar.after("bear:stay", function () {
  console.log(this.name + " stayed.");
});

bear.leave();
bear.stay();

// Bear is thinking about leaving...
// Bear is leaving...
// Bear is thinking about staying...
// Bear is staying...
// Bear left.
// Bear stayed.

Sync vs. Async

This library works with both synchronous and asynchronous methods, but it does require an adherence to a certain asynchronous convention -- callback parameters MUST be the last parameter supplied to a method. For example...

var okay = radar.wrap({
  asyncMethod: function (name, done) {
    done(null, name.toUpperCase());
  }
}, { prefix: "okay" });

var notOkay = radar.wrap({
  asyncMethod: function (done, name) {
    done(null, name.toUpperCase());
  }
}, { prefix: "notOkay" });

API

Radar(options) constructor

Create a new Radar object with some optional configuration.

Usage

var radar = new Radar();
var radar = new Radar({ methods: ["leave"] });

Arguments

Options

Radar.wrap(object, options)

Wraps designated methods within an object with before and after event emitters.

Usage

var bear = radar.wrap({
  name:  "Bear",
  leave: function () {
    console.log(this.name + " is leaving...");
  }
}, { prefix: "bear" });

var fox = radar.wrap({
  name: "Fox",
  stay: function () {
    console.log(this.name + " is staying...");
  }
}, {
  prefix:    "fox",
  separator: "/"
  methods:   ["stay"]
})

Arguments

Options

Radar.before(eventName, handler)

Trigger handler before the wrapped method is called on the object. The context (this) within this method is the object which the event was registered against.

Usage

radar.before("bear:leave", function () {
  console.log(this.name + " is about to leave..."); // Bear is about to leave...
});

Arguments

Radar.after(eventName, handler)

Trigger handler after the wrapped method is called on the object. The context (this) within this method is the object which the event was registered against.

Usage

radar.after("bear:leave", function () {
  console.log(this.name + " left."); // Bear left.
});

Arguments

License

MIT