下面是另一种方法。这也可以用于粘贴。[用于字母-数字验证]

//Input Validation
var existingLogDescription = "";

$('.logDescription').keydown(function (event) {
    existingLogDescription = this.value;

});


$('.logDescription').keyup(function () {
    if (this.value.match(/[^a-zA-Z0-9 ]/g)) {
        alert("Log Description should contain alpha-numeric values only");
        this.value = this.value.replace(/[^a-zA-Z0-9 ]/g, '');
        this.value = existingLogDescription;
    }
});

$(document).ready(function() {
    $("#txtboxToFilter").keydown(function(event) {
        // Allow only backspace and delete
        if ( event.keyCode == 46 || event.keyCode == 8 ) {
            // let it happen, don't do anything
        }
        else {
            // Ensure that it is a number and stop the keypress
            if (event.keyCode < 48 || event.keyCode > 57 ) {
                event.preventDefault(); 
            }   
        }
    });
});

来源:http://snipt.net/GerryEng/jquery-making-textfield-only-accept-numeric-values

如果你必须解决变音符和特殊字符，尝试使用这个:

$(this).on( 'keypress', function( e )
{
    // Ensure that it is a number and stop the keypress
    if (e.shiftKey || (e.keyCode < 48 || e.keyCode > 57)) {
        e.preventDefault();
    }
});  

/**
Makes the textbox to accept only numeric input
*/

(function($) {
    $.fn.allowOnlyNumeric = function() {

        /**
        The interval code is commented as every 250 ms onchange of the textbox gets fired.
        */

        //  var createDelegate = function(context, method) {
        //      return function() { method.apply(context, arguments); };
        //  };

        /**
        Checks whether the key is only numeric.
        */
        var isValid = function(key) {
            var validChars = "0123456789";
            var validChar = validChars.indexOf(key) != -1;
            return validChar;
        };

        /**
        Fires the key down event to prevent the control and alt keys
        */
        var keydown = function(evt) {
            if (evt.ctrlKey || evt.altKey) {
                evt.preventDefault();
            }
        };

        /**
        Fires the key press of the text box   
        */
        var keypress = function(evt) {
            var scanCode;
            //scanCode = evt.which;
            if (evt.charCode) { //For ff
                scanCode = evt.charCode;
            }
            else { //For ie
                scanCode = evt.keyCode;
            }

            if (scanCode && scanCode >= 0x20 /* space */) {
                var c = String.fromCharCode(scanCode);
                if (!isValid(c)) {
                    evt.preventDefault();
                }
            }
        };

        /**
        Fires the lost focus event of the textbox   
        */
        var onchange = function() {
            var result = [];
            var enteredText = $(this).val();
            for (var i = 0; i < enteredText.length; i++) {
                var ch = enteredText.substring(i, i + 1);
                if (isValid(ch)) {
                    result.push(ch);
                }
            }
            var resultString = result.join('');
            if (enteredText != resultString) {
                $(this).val(resultString);
            }

        };

        //var _filterInterval = 250;
        //var _intervalID = null;

        //var _intervalHandler = null;

        /**
        Dispose of the textbox to unbind the events.
        */
        this.dispose = function() {
            $(this).die('change', onchange);
            $(this).die('keypress', keypress);
            $(this).die('keydown', keydown);
            //window.clearInterval(_intervalHandler);
        };

        $(this).live('change', onchange);
        $(this).live('keypress', keypress);
        $(this).live('keydown', keydown);
        //_intervalHandler = createDelegate(this, onchange);
        //_intervalID = window.setInterval(_intervalHandler, _filterInterval);
    }
})(jQuery);

上面的$ plugin是从AjaxControlToolkit过滤器文本框extender.js编写的。

然而，有一个行为并没有从AjaxControlToolkit中借用，那就是当用户复制和粘贴任何非数字值时，onchange事件就会触发，文本框就会吞噬这些值。我检查了代码，发现这个onchange在每250ms之后被调用，这是一个性能打击，因此注释了这部分。

$(document).ready(function()
{
    $("#textBoxId").bind("change",checkInput);
});

function checkInput()
{
    // check if $('#textBoxId').val() is under your constraints
    // then change its value, removing the last character
    // since this event will be called each time you
    // type a character
}

使用JavaScript函数isNaN，

if (isNaN($('#inputid').val()))

if （isNaN（document.getElementById（'inputid'）.val（）））

if (isNaN(document.getElementById('inputid').value))

更新: 这里有一篇很好的文章谈论它，但使用jQuery:限制输入在HTML文本框的数值