js 限制文本只能输入数字

function limitNumber(event)
        {
            var keyCode = event.keyCode | event.charCode;

            if (!((keyCode > 47 && keyCode < 58)
                || (keyCode > 95 && keyCode < 106)
                || keyCode == 13
                || keyCode == 8))
            {
                event.returnValue = false;
            }
        }

        function setLimitNumberInput(id)
        {
            var objTarget = document.getElementById(id);

            if (objTarget == null)
            {
                return;
            }

            objTarget.onkeydown = function()
            {
                limitNumber(event);
            };

            objTarget.onpaste = function()
            {
                limitNumber(event);
            };

            objTarget.ondrop = function()
            {
                limitNumber(event);
            };
        }