1.文本框只能输入数字代码(小数点也不能输入) 
<input onkeyup="this.value=this.value.replace(/D/g,'')" onafterpaste="this.value=this.value.replace(/D/g,'')">
2.只能输入数字,能输小数点.<input onkeyup="if(isNaN(value))execCommand('undo')" onafterpaste="if(isNaN(value))execCommand('undo')"><input name=txt1 onchange="if(/D/.test(this.value)){alert('只能输入数字');this.value='';}">
3.数字和小数点方法二<input type=text t_value="" o_value="" onkeypress="if(!this.value.match(/^[+-]?d*?.?d*?$/))this.value=this.t_value;else this.t_value=this.value;if(this.value.match(/^(?:[+-]?d+(?:.d+)?)?$/))this.o_value=this.value" onkeyup="if(!this.value.match(/^[+-]?d*?.?d*?$/))this.value=this.t_value;else this.t_value=this.value;if(this.value.match(/^(?:[+-]?d+(?:.d+)?)?$/))this.o_value=this.value" onblur="if(!this.value.match(/^(?:[+-]?d+(?:.d+)?|.d*?)?$/))this.value=this.o_value;else{if(this.value.match(/^.d+$/))this.value=0+this.value;if(this.value.match(/^.$/))this.value=0;this.o_value=this.value}">
4.只能输入字母和汉字<input onkeyup="value=value.replace(/[d]/g,'') "onbeforepaste="clipboardData.setData('text',clipboardData.getData('text').replace(/[d]/g,''))" maxlength=10 name="Numbers">
5.只能输入英文字母和数字,不能输入中文<input onkeyup="value=value.replace(/[^w./]/ig,'')">
6.只能输入数字和英文<font color="Red">chun</font><input onKeyUp="value=value.replace(/[^d|chun]/g,'')">
7.小数点后只能有最多两位(数字,中文都可输入),不能输入字母和运算符号:<input onKeyPress="if((event.keyCode<48 || event.keyCode>57) && event.keyCode!=46 || /.dd$/.test(value))event.returnValue=false">
8.小数点后只能有最多两位(数字,字母,中文都可输入),可以输入运算符号:<input onkeyup="this.value=this.value.replace(/^(-)*(d+).(dd).*$/,'$1$2.$3')">