如果你可以使用插件，这里有一个我测试过的。除了膏体外，效果很好。

数字输入

这里是一个演示http://jsfiddle.net/152sumxu/2

下面的代码(库内粘贴)

<div id="plugInDemo" class="vMarginLarge">
    <h4>Demo of the plug-in    </h4>
    <div id="demoFields" class="marginSmall">
        <div class="vMarginSmall">
            <div>Any Number</div>
            <div>
                <input type="text" id="anyNumber" />
            </div>
        </div>
    </div>
</div>

<script type="text/javascript">
    //    Author: Joshua De Leon - File: numericInput.js - Description: Allows only numeric input in an element. - If you happen upon this code, enjoy it, learn from it, and if possible please credit me: www.transtatic.com
    (function(b) {
        var c = { allowFloat: false, allowNegative: false};
        b.fn.numericInput = function(e) {
            var f = b.extend({}, c, e);
            var d = f.allowFloat;
            var g = f.allowNegative;
            this.keypress(function(j) {
                var i = j.which;
                var h = b(this).val();
                if (i>0 && (i<48 || i>57)) {
                    if (d == true && i == 46) {
                        if (g == true && a(this) == 0 && h.charAt(0) == "-") {
                            return false
                        }
                        if (h.match(/[.]/)) {
                            return false
                        }
                    }
                    else {
                        if (g == true && i == 45) {
                            if (h.charAt(0) == "-") {
                                return false
                            }
                            if (a(this) != 0) {
                                return false
                            }
                        }
                        else {
                            if (i == 8) {
                                return true
                            }
                            else {
                                return false
                            }
                        }
                    }
                }
                else {
                    if (i>0 && (i >= 48 && i <= 57)) {
                        if (g == true && h.charAt(0) == "-" && a(this) == 0) {
                            return false
                        }
                    }
                }
            });
            return this
        };
        function a(d) {
            if (d.selectionStart) {
                return d.selectionStart
            }
            else {
                if (document.selection) {
                    d.focus();
                    var f = document.selection.createRange();
                    if (f == null) {
                        return 0
                    }
                    var e = d.createTextRange(), g = e.duplicate();
                    e.moveToBookmark(f.getBookmark());
                    g.setEndPoint("EndToStart", e);
                    return g.text.length
                }
            }
            return 0
        }
    }(jQuery));

    $(function() {
       $("#anyNumber").numericInput({ allowFloat: true, allowNegative: true });
    });
</script>

你可以附加到key down事件，然后根据你需要过滤键，例如:

<input id="FIELD_ID" name="FIELD_ID" onkeypress="return validateNUM(event,this);"  type="text">

实际的JavaScript处理程序是:

function validateNUM(e,field)
{
    var key = getKeyEvent(e)
    if (specialKey(key)) return true;
    if ((key >= 48 && key <= 57) || (key == 46)){
        if (key != 46)
            return true;
        else{
            if (field.value.search(/\./) == -1 && field.value.length > 0)
                return true;
            else
                return false;
        }
    }

function getKeyEvent(e){
    var keynum
    var keychar
    var numcheck
    if(window.event) // IE
        keynum = e.keyCode
    else if(e.which) // Netscape/Firefox/Opera
        keynum = e.which
    return keynum;
}

最好的方法(允许所有类型的数字-实负，实正，iinteger负，整数正)是:

$(input).keypress(function (evt){
    var theEvent = evt || window.event;
    var key = theEvent.keyCode || theEvent.which;
    key = String.fromCharCode( key );
    var regex = /[-\d\.]/; // dowolna liczba (+- ,.) :)
    var objRegex = /^-?\d*[\.]?\d*$/;
    var val = $(evt.target).val();
    if(!regex.test(key) || !objRegex.test(val+key) || 
            !theEvent.keyCode == 46 || !theEvent.keyCode == 8) {
        theEvent.returnValue = false;
        if(theEvent.preventDefault) theEvent.preventDefault();
    };
}); 

一个使用jQuery和replace()而不是查看事件的简短而甜蜜的实现。keyCode或event.which:

$('input.numeric').live('keyup', function(e) {
  $(this).val($(this).val().replace(/[^0-9]/g, ''));
});

只有一个小的副作用，输入的字母出现暂时和CTRL/CMD + A似乎表现有点奇怪。

JavaScript

function validateNumber(evt) {
    var e = evt || window.event;
    var key = e.keyCode || e.which;

    if (!e.shiftKey && !e.altKey && !e.ctrlKey &&
    // numbers   
    key >= 48 && key <= 57 ||
    // Numeric keypad
    key >= 96 && key <= 105 ||
    // Backspace and Tab and Enter
    key == 8 || key == 9 || key == 13 ||
    // Home and End
    key == 35 || key == 36 ||
    // left and right arrows
    key == 37 || key == 39 ||
    // Del and Ins
    key == 46 || key == 45) {
        // input is VALID
    }
    else {
        // input is INVALID
        e.returnValue = false;
        if (e.preventDefault) e.preventDefault();
    }
}

你可以添加逗号，句号和减号(，.-)

  // comma, period and minus, . on keypad
  key == 190 || key == 188 || key == 109 || key == 110 ||

HTML

<input type="text" onkeydown="validateNumber(event);"/ >

是的，HTML5可以。试试下面的代码(w3school):

<!DOCTYPE html>
<html>
<body>

<form action="">
  Quantity (between 1 and 5): <input type="number" name="quantity" min="1" max="5" />
  <input type="submit" />
</form>

</body>
</html>