Example of an input manager to go w/ nengi

InputManager.js

var EventEmitter = require('../../nengi/external/EventEmitter')
function InputManager() {
	EventEmitter.call(this)

	// tracks the real time state of W A S D
	this.W = false
	this.A = false
	this.S = false
	this.D = false

	this.currentKeyState = new KeyState()
	this.previousKeyState = new KeyState()

	var self = this
	/*
	* If W A S D are ever tapped, then they count as pressed
	* for a whole frame.
	*/
	document.addEventListener('keydown', function(e) {
		// W A S D or arrow keys
		if (e.keyCode === 87 || e.keyCode === 38) { 
			self.W = true
			self.currentKeyState.W = true
		} 
		if (e.keyCode === 65 || e.keyCode === 37) { 
			self.A = true
			self.currentKeyState.A = true
		}
		if (e.keyCode === 83 || e.keyCode === 40) { 
			self.S = true 
			self.currentKeyState.S = true
		}
		if (e.keyCode === 68 || e.keyCode === 39) { 
			self.D = true
			self.currentKeyState.D = true
		}
	})

	document.addEventListener('keyup', function(e) {
		// W or up arrow
		if (e.keyCode === 87 || e.keyCode === 38) { self.W = false }
		// A or left arrow
		if (e.keyCode === 65 || e.keyCode === 37) { self.A = false }
		// S or down arrow
		if (e.keyCode === 83 || e.keyCode === 40) { self.S = false }
		// D or right arrow
		if (e.keyCode === 68 || e.keyCode === 39) { self.D = false }
	})

	document.addEventListener('mousedown', function(e) {
		var mouseX = 0
		var mouseY = 0

		if (typeof e.offsetX !== 'undefined' && typeof e.offsetY !== 'undefined') { 
			mouseX = e.offsetX
			mouseY = e.offsetY
		} else {
			mouseX = e.layerX
			mouseY = e.layerY
		}

		var rightclick
		if (!e) var e = window.e
		if (e.which) rightclick = (e.which == 3)
		else if (e.button) rightclick = (e.button == 2)

		if (rightclick) {
			// right click detected
			//console.log('right click')
			//e.preDefault()
		} else {
			self.emit('mouseDown', mouseX, mouseY)
		}
	})

	document.addEventListener('mouseup', function(e) {
		var mouseX = 0
		var mouseY = 0

		if (typeof e.offsetX !== 'undefined' && typeof e.offsetY !== 'undefined') { 
			mouseX = e.offsetX
			mouseY = e.offsetY
		} else {
			mouseX = e.layerX
			mouseY = e.layerY
		}

		self.emit('mouseUp', mouseX, mouseY)
	})


}
InputManager.prototype = Object.create(EventEmitter.prototype)
InputManager.prototype.constructor = InputManager

function KeyState() {
	this.W = false
	this.A = false
	this.S = false
	this.D = false
}

InputManager.prototype.update = function() {
	this.emit('keyState', this.previousKeyState)

	this.previousKeyState = this.currentKeyState
	this.currentKeyState = new KeyState()
	// if a key is still held down, count it as pressed again
	if (this.W) {
		this.currentKeyState.W = true
	}
	if (this.A) {
		this.currentKeyState.A = true
	}
	if (this.S) {
		this.currentKeyState.S = true
	}
	if (this.D) {
		this.currentKeyState.D = true
	}
}

module.exports = InputManager