用Jquery控制文本框只能输入数字和字母

$.fn.onlyNum = function () {
$(this).keypress(function (event) {
var eventObj = event || e;
var keyCode = eventObj.keyCode || eventObj.which;
if ((keyCode >= 48 && keyCode <= 57) || ((keyCode == 8 || keyCode == 46)))
return true;
else
return false;
}).focus(function () {
//禁用输入法
this.style.imeMode = 'disabled';
});
};