countdown

countdown.js

var countArr = [];
var Countdown = function(options) {
    this.max = options.max;
	this.obj = options.obj;
	this.remaining = this.max - $(this.obj).val().length;
};

Countdown.prototype.updateRemaining = function() {
	if (this.remaining > this.max) {
        this.remaining = this.max;
    }
    if ($(this.obj).val().length > this.max) {
    	this.remaining = 0;
    }
    if(this.remaining !=0) {
    	this.remaining = this.max - $(this.obj).val().length;
    }

    return this.remaining;
};

$(".countdown").each(function() {

    $(this).focus(function() {
        var c = $(this).attr("class");
        var countdownObj = new Countdown({
            obj:this,
            max:parseInt(c.match(/limit_[0-9]{1,}_/)[0].match(/[0-9]{1,}/)[0])
        });
        countArr[$(this).attr("id")] = countdownObj;
    }).bind('keyup blur', function() {
        var countdownObj = countArr[$(this).attr("id")];
        var lettersLeft = countdownObj.updateRemaining();

        $("."+ $(this).attr("id")+"_remaining").html("(" + lettersLeft + " characters remaining.)");
    });

});