throbber.js

"use strict";

var compose      = require("es5-ext/function/#/compose")
  , callable     = require("es5-ext/object/valid-callable")
  , d            = require("d")
  , validTimeout = require("timers-ext/valid-timeout");

var chars = "-\\|/", l = chars.length, ThrobberIterator;

ThrobberIterator = function () {
	// no setup needed
};
Object.defineProperties(ThrobberIterator.prototype, {
	index: d(-1),
	running: d(false),
	next: d(function () {
		var str = this.running ? "\u0008" : "";
		if (!this.running) this.running = true;
		return str + chars[(this.index = (this.index + 1) % l)];
	}),
	reset: d(function () {
		if (!this.running) return "";
		this.index = -1;
		this.running = false;
		return "\u0008";
	})
});

module.exports = exports = function (write, interval /*, format*/) {
	var format = arguments[2], token, iterator = new ThrobberIterator();
	callable(write);
	interval = validTimeout(interval);
	if (format !== undefined) write = compose.call(write, callable(format));
	return {
		start: function () {
			if (token) return;
			token = setInterval(function () { write(iterator.next()); }, interval);
		},
		restart: function () {
			this.stop();
			this.start();
		},
		stop: function () {
			if (!token) return;
			clearInterval(token);
			token = null;
			write(iterator.reset());
		}
	};
};

Object.defineProperty(exports, "Iterator", d(ThrobberIterator));