Javascript: Utility library

utils.js

/**
 *  utils.js
 *
 *  @author Niko Heikkilä (@ytserman) <http://scr.im/ytserman>
 *
 *  Contains several utility functions for cross-browser compatibility.
 *  Drop this into your javascript folder and call before other scripts.
 *
 */
function createRequest() {

	/**
	 *  createRequest
	 *
	 *  Creates necessary XHR to use with AJAX apps if possible.
	 *  Supports all browsers.
	 *
	 *  @return XMLHTTPRequest || null
	 */

	try {

		request = new XMLHttpRequest();

	} catch (tryMS) {

		try {

			request = new ActiveXObject("Msxml2.XMLHTTP");

		} catch (otherMS) {

		try {

			request = new ActiveXObject("Microsoft.XMLHTTP");

			} catch (failed) {

			request = null;
			}
		}
	}

	return request;
}

function isArray(arg) {
	
	/**
	 *  isArray
	 *
	 *  Checks if passed object is an array
	 *
	 *  @param arg Object to check
	 *  @return bool
	 */

	if (typeof arg == 'object') {
		
		var criteria = arg.constructor.toString().match(/array/i);

		return (criteria != null);
	}

	return false;
}

function addEventHandler(obj, eventName, handler) {

	/**
	 *  addEventHandler
	 *
	 *  Attach event handlers the way your browser likes.
	 *  NOTE: IE 9 supports DOM Level 2.
	 *
	 *  @param obj          object to attach to
	 *  @param eventName    name of the event
	 *  @param handler      handler function to run
	 *  @return void
	 */

	if (document.attachEvent) {

		/* For browsers that don't support DOM Level 2. */
		obj.attachEvent("on" + eventName, handler);

	} else if (document.addEventListener) {

		/* For modern browsers. */
		obj.addEventListener(eventName, handler, false);
	}
}

function getActivatedObject(e) {

	/**
	 *  getActivatedObject
	 *
	 *  Function takes the passed argument from browser
	 *  and figures out which activated object to return
	 *
	 *  @param e    Event object for handlers
	 *
	 *  @return obj Desired activated object
	 */

	var obj;

	if (!e) {

		/* Early versions of IE */
		obj = window.event.srcElement;

	} else if (e.srcElement) {

		/* IE 7 or later */
		obj = e.srcElement;

	} else {

		/* DOM Level 2 browsers */
		obj = e.target;
	}

	return obj;
}

function fieldIsFilled(e) {
	
	var me = getActivatedObject(e);

	if (me.value == "") {
		
		warn(me, "required");

	} else {
		
		unwarn(me, "required");
	}
}

function emailIsProper(e) {
	
	var me = getActivatedObject(e);
	var properEmail = /^[\w\.-_\+]+@[\w-]+(\.\w{2,4})+$/;

	if ( ! properEmail.test(me.value)) {
		
		warn(me, "format");

	} else {
		
		unwarn(me, "format");
	}
}

function fieldIsLetters(e) {
	
	var me = getActivatedObject(e);
	var nonAlphaChars = /[^a-zA-Z]/;

	if (nonAlphaChars.test(me.value)) {
		
		warn(me, "letters");

	} else {
		
		unwarn(me, "letters");
	}
}

function fieldIsNumbers(e) {
	
	var me = getActivatedObject(e);
	var nonNumericChars = /[0-9]/;

	if (nonNumericChars.test(me.value)) {
		
		// Error
	} else {
		
		// No.
	}
}

/* End of file utils.js */