Only Positive Integer allow in Textbox using JQuery

jquery.numeric.js

/*
 *
 * Copyright (c) 2006-2011 Sam Collett (http://www.texotela.co.uk)
 * Dual licensed under the MIT (http://www.opensource.org/licenses/mit-license.php)
 * and GPL (http://www.opensource.org/licenses/gpl-license.php) licenses.
 * 
 * Version 1.3
 * Demo: http://www.texotela.co.uk/code/jquery/numeric/
 *
 */
(function($) {
/*
 * Allows only valid characters to be entered into input boxes.
 * Note: fixes value when pasting via Ctrl+V, but not when using the mouse to paste
  *      side-effect: Ctrl+A does not work, though you can still use the mouse to select (or double-click to select all)
 *
 * @name     numeric
 * @param    config      { decimal : "." , negative : true }
 * @param    callback     A function that runs if the number is not valid (fires onblur)
 * @author   Sam Collett (http://www.texotela.co.uk)
 * @example  $(".numeric").numeric();
 * @example  $(".numeric").numeric(","); // use , as separater
 * @example  $(".numeric").numeric({ decimal : "," }); // use , as separator
 * @example  $(".numeric").numeric({ negative : false }); // do not allow negative values
 * @example  $(".numeric").numeric(null, callback); // use default values, pass on the 'callback' function
 *
 */
$.fn.numeric = function(config, callback)
{
  if(typeof config === 'boolean')
	{
		config = { decimal: config };
	}
	config = config || {};
	// if config.negative undefined, set to true (default is to allow negative numbers)
	if(typeof config.negative == "undefined") config.negative = true;
	// set decimal point
	var decimal = (config.decimal === false) ? "" : config.decimal || ".";
	// allow negatives
	var negative = (config.negative === true) ? true : false;
	// callback function
	var callback = typeof callback == "function" ? callback : function(){};
	// set data and methods
	return this.data("numeric.decimal", decimal).data("numeric.negative", negative).data("numeric.callback", callback).keypress($.fn.numeric.keypress).keyup($.fn.numeric.keyup).blur($.fn.numeric.blur);
}

$.fn.numeric.keypress = function(e)
{
	// get decimal character and determine if negatives are allowed
	var decimal = $.data(this, "numeric.decimal");
	var negative = $.data(this, "numeric.negative");
	// get the key that was pressed
	var key = e.charCode ? e.charCode : e.keyCode ? e.keyCode : 0;
	// allow enter/return key (only when in an input box)
	if(key == 13 && this.nodeName.toLowerCase() == "input")
	{
		return true;
	}
	else if(key == 13)
	{
		return false;
	}
	var allow = false;
	// allow Ctrl+A
	if((e.ctrlKey && key == 97 /* firefox */) || (e.ctrlKey && key == 65) /* opera */) return true;
	// allow Ctrl+X (cut)
	if((e.ctrlKey && key == 120 /* firefox */) || (e.ctrlKey && key == 88) /* opera */) return true;
	// allow Ctrl+C (copy)
	if((e.ctrlKey && key == 99 /* firefox */) || (e.ctrlKey && key == 67) /* opera */) return true;
	// allow Ctrl+Z (undo)
	if((e.ctrlKey && key == 122 /* firefox */) || (e.ctrlKey && key == 90) /* opera */) return true;
	// allow or deny Ctrl+V (paste), Shift+Ins
	if((e.ctrlKey && key == 118 /* firefox */) || (e.ctrlKey && key == 86) /* opera */
	|| (e.shiftKey && key == 45)) return true;
	// if a number was not pressed
	if(key < 48 || key > 57)
	{
		/* '-' only allowed at start and if negative numbers allowed */
		if(this.value.indexOf("-") != 0 && negative && key == 45 && (this.value.length == 0 || ($.fn.getSelectionStart(this)) == 0)) return true;
		/* only one decimal separator allowed */
		if(decimal && key == decimal.charCodeAt(0) && this.value.indexOf(decimal) != -1)
		{
			allow = false;
		}
		// check for other keys that have special purposes
		if(
			key != 8 /* backspace */ &&
			key != 9 /* tab */ &&
			key != 13 /* enter */ &&
			key != 35 /* end */ &&
			key != 36 /* home */ &&
			key != 37 /* left */ &&
			key != 39 /* right */ &&
			key != 46 /* del */
		)
		{
			allow = false;
		}
		else
		{
			// for detecting special keys (listed above)
			// IE does not support 'charCode' and ignores them in keypress anyway
			if(typeof e.charCode != "undefined")
			{
				// special keys have 'keyCode' and 'which' the same (e.g. backspace)
				if(e.keyCode == e.which && e.which != 0)
				{
					allow = true;
					// . and delete share the same code, don't allow . (will be set to true later if it is the decimal point)
					if(e.which == 46) allow = false;
				}
				// or keyCode != 0 and 'charCode'/'which' = 0
				else if(e.keyCode != 0 && e.charCode == 0 && e.which == 0)
				{
					allow = true;
				}
			}
		}
		// if key pressed is the decimal and it is not already in the field
		if(decimal && key == decimal.charCodeAt(0))
		{
			if(this.value.indexOf(decimal) == -1)
			{
				allow = true;
			}
			else
			{
				allow = false;
			}
		}
	}
	else
	{
		allow = true;
	}
	return allow;
}

$.fn.numeric.keyup = function(e)
{
	var val = this.value;
	if(val.length > 0)
	{
		// get carat (cursor) position
		var carat = $.fn.getSelectionStart(this);
		// get decimal character and determine if negatives are allowed
		var decimal = $.data(this, "numeric.decimal");
		var negative = $.data(this, "numeric.negative");
		
		// prepend a 0 if necessary
		if(decimal != "")
		{
			// find decimal point
			var dot = val.indexOf(decimal);
			// if dot at start, add 0 before
			if(dot == 0)
			{
				this.value = "0" + val;
			}
			// if dot at position 1, check if there is a - symbol before it
			if(dot == 1 && val.charAt(0) == "-")
			{
				this.value = "-0" + val.substring(1);
			}
			val = this.value;
		}
		
		// if pasted in, only allow the following characters
		var validChars = [0,1,2,3,4,5,6,7,8,9,'-',decimal];
		// get length of the value (to loop through)
		var length = val.length;
		// loop backwards (to prevent going out of bounds)
		for(var i = length - 1; i >= 0; i--)
		{
			var ch = val.charAt(i);
			// remove '-' if it is in the wrong place
			if(i != 0 && ch == "-")
			{
				val = val.substring(0, i) + val.substring(i + 1);
			}
			// remove character if it is at the start, a '-' and negatives aren't allowed
			else if(i == 0 && !negative && ch == "-")
			{
				val = val.substring(1);
			}
			var validChar = false;
			// loop through validChars
			for(var j = 0; j < validChars.length; j++)
			{
				// if it is valid, break out the loop
				if(ch == validChars[j])
				{
					validChar = true;
					break;
				}
			}
			// if not a valid character, or a space, remove
			if(!validChar || ch == " ")
			{
				val = val.substring(0, i) + val.substring(i + 1);
			}
		}
		// remove extra decimal characters
		var firstDecimal = val.indexOf(decimal);
		if(firstDecimal > 0)
		{
			for(var i = length - 1; i > firstDecimal; i--)
			{
				var ch = val.charAt(i);
				// remove decimal character
				if(ch == decimal)
				{
					val = val.substring(0, i) + val.substring(i + 1);
				}
			}
		}
		// set the value and prevent the cursor moving to the end
		this.value = val;
		$.fn.setSelection(this, carat);
	}
}

$.fn.numeric.blur = function()
{
	var decimal = $.data(this, "numeric.decimal");
	var callback = $.data(this, "numeric.callback");
	var val = this.value;
	if(val != "")
	{
		var re = new RegExp("^\\d+$|\\d*" + decimal + "\\d+");
		if(!re.exec(val))
		{
			callback.apply(this);
		}
	}
}

$.fn.removeNumeric = function()
{
	return this.data("numeric.decimal", null).data("numeric.negative", null).data("numeric.callback", null).unbind("keypress", $.fn.numeric.keypress).unbind("blur", $.fn.numeric.blur);
}

// Based on code from http://javascript.nwbox.com/cursor_position/ (Diego Perini <dperini@nwbox.com>)
$.fn.getSelectionStart = function(o)
{
	if (o.createTextRange)
	{
		var r = document.selection.createRange().duplicate();
		r.moveEnd('character', o.value.length);
		if (r.text == '') return o.value.length;
		return o.value.lastIndexOf(r.text);
	} else return o.selectionStart;
}

// set the selection, o is the object (input), p is the position ([start, end] or just start)
$.fn.setSelection = function(o, p)
{
	// if p is number, start and end are the same
	if(typeof p == "number") p = [p, p];
	// only set if p is an array of length 2
	if(p && p.constructor == Array && p.length == 2)
	{
		if (o.createTextRange)
		{
			var r = o.createTextRange();
			r.collapse(true);
			r.moveStart('character', p[0]);
			r.moveEnd('character', p[1]);
			r.select();
		}
		else if(o.setSelectionRange)
		{
			o.focus();
			o.setSelectionRange(p[0], p[1]);
		}
	}
}

})(jQuery);

PositiveInteger.js

$(".positive-integer").numeric({ decimal: false, negative: false }, function () { alert("Positive integers only"); this.value = ""; this.focus(); });