formfieldlimiter.js

//** Form field Limiter v2.0- (c) Dynamic Drive DHTML code library: http://www.dynamicdrive.com
//** Feb 25th, 09'- Script creation date
//** This notice must stay intact for legal use

var fieldlimiter={

defaultoutput: "<b>[int]</b> characters remaining in your input limit.", //default message that gets output to statusid element

uncheckedkeycodes: /(8)|(13)|(16)|(17)|(18)/, //keycodes that are not checked, even when limit has been reached. See http://www.javascriptkit.com/jsref/eventkeyboardmouse.shtml for avail keycodes

limitinput:function(e, config){
	var e=window.event || e
	var thefield=config.thefield
	var keyunicode=e.charCode || e.keyCode
	if (!this.uncheckedkeycodes.test(keyunicode)){
		if (thefield.value.length>=config.maxlength){
			if (e.preventDefault)
				e.preventDefault()
			return false
		}
	}
},

showlimit:function(config){
	var thefield=config.thefield
	var statusids=config.statusids
	var charsleft=config.maxlength-thefield.value.length
	if (charsleft<0) //if user has exceeded input limit (possible if cut and paste text into field)
		thefield.value=thefield.value.substring(0, config.maxlength) //trim input
	for (var i=0; i<statusids.length; i++){
		var statusdiv=document.getElementById(statusids[i])
		if (statusdiv) //if status DIV defined
			statusdiv.innerHTML=this.defaultoutput.replace("[int]", Math.max(0, charsleft))
	}
	config.onkeypress.call(thefield, config.maxlength, thefield.value.length)
},

cleanup:function(config){
	for (var prop in config){
		config[prop]=null
	}
},


addEvent:function(targetarr, functionref, tasktype){
	if (targetarr.length>0){
		var target=targetarr.shift()
		if (target.addEventListener)
			target.addEventListener(tasktype, functionref, false)
		else if (target.attachEvent)
			target.attachEvent('on'+tasktype, function(){return functionref.call(target, window.event)})
		this.addEvent(targetarr, functionref, tasktype)
	}
},

setup:function(config){
	if (config.thefield){ //if form field exists
		config.onkeypress=config.onkeypress || function(){}
		config.thefield.value=config.thefield.value
		this.showlimit(config)
		this.addEvent([window], function(e){fieldlimiter.showlimit(config)}, "load")
		this.addEvent([window], function(e){fieldlimiter.cleanup(config)}, "unload")		
		this.addEvent([config.thefield], function(e){return fieldlimiter.limitinput(e, config)}, "keypress")
		this.addEvent([config.thefield], function(){fieldlimiter.showlimit(config)}, "keyup")
	}
}

}