morse-beep/index.js

A simple text to Morse Code player for the modern web

var lettersToMorse = {
	"a": "sl",
	"b": "lsss",
	"c": "lsls",
	"d": "lss",
	"e": "s",
	"f": "ssls",
	"g": "lls",
	"h": "ssss",
	"i": "ss",
	"j": "slll",
	"k": "lsl",
	"l": "slss",
	"m": "ll",
	"n": "ls",
	"o": "lll",
	"p": "slls",
	"q": "llsl",
	"r": "sls",
	"s": "sss",
	"t": "l",
	"u": "ssl",
	"v": "sssl",
	"w": "sll",
	"x": "lssl",
	"y": "lsll",
	"z": "llss",
	"1": "sllll",
	"2": "sslll",
	"3": "sssll",
	"4": "ssssl",
	"5": "sssss",
	"6": "lssss",
	"7": "llsss",
	"8": "lllss",
	"9": "lllls",
	"0": "lllll"
}

module.exports = function(opts){

	opts = opts || {};
	var unit = opts.unit || 25;
	var gap = opts.gap || 10;

	var beeper = require("./lib/beep")(0);

	var beep = function(num, cb){
		var type = num == unit ? "dit" : "dah";

		emit("start-beep", type);
		beeper(gap*num, function(){
			emit("end-beep", type);
			setTimeout(cb, unit*gap);
		});
	}

	var long = function(cb){
		cb = cb || function(){};
		beep(3*unit, cb);
	}

	var short = function(cb){
		cb = cb || function(){};
		beep(unit, cb);
	}

	var pause = function(cb){
		setTimeout(cb, 2*unit*gap);
	}

	var space = function(cb){
		setTimeout(cb, 4*unit*gap);
	}

	var parse = function(str,cb){
		if(str.length){
			var l = str[0];
			str = str.slice(1);
			if(l=="s"){
				short(function(){
					parse(str,cb);
				});
			}
			else{
				long(function(){
					parse(str, cb);
				});
			}
		}
		else{
			pause(cb);
		}
	}

	var say = function(msg, cb){
		if(msg.length){
			var l = msg[0];
			emit("start-letter", l);
			msg = msg.slice(1);
			var code = lettersToMorse[l];
			if(code){
				parse(code, function(){
					emit("end-letter", l);
					say(msg, cb);
				});
			}
			else if(l==" "){
				space(function(){
					emit("end-letter", l);
					say(msg, cb);
				});
			}
			else{
				emit("end-letter", l);
				say(msg, cb);
			}
		} 
		else{
			cb();
		}
	}

	var listeners = {"start":[], "stop":[]};

	var emit = function(key, value){
		listeners[key] = listeners[key] || [];
		for(var i=0; i<listeners[key].length; i++){
			listeners[key][i](value);
		}
	}

	var sayer = function(msg, cb){
		cb = cb || function(){};
		msg = msg.toLowerCase();
		say(msg, cb);
	}

	sayer.on = function(key, fn){
		listeners[key] = listeners[key] || [];
		listeners[key].push(fn);
	}

	return sayer;
}