1.文本框只能输入数字代码(小数点也不能输入)
<inputonkeyup="this.value=this.value.replace(/\D/g,'')"onafterpaste="this.value=this.value.replace(/\D/g,'')">

或

<input onkeyup="if(this.value.length==1){this.value=this.value.replace(/[^1-9]/g,'')}else{this.value=this.value.replace(/\D/g,'')}" onafterpaste="if(this.value.length==1){this.value=this.value.replace(/[^1-9]/g,'')}">

2.只能输入数字,能输小数点.

<inputtype="text"size="12"onkeyup="this.value=this.value.replace(/[^\d\.]+?/g,'')"/>
<inputonkeyup="if(isNaN(value))execCommand('undo')"onafterpaste="if(isNaN(value))execCommand('undo')">
<inputname=txt1onchange="if(/\D/.test(this.value)){alert('只能输入数字');this.value='';}">

3.数字和小数点方法二
<inputtype=texttvalue=""ovalue=""onkeypress="if(!this.value.match(/^[\+\-]?\d*?\.?\d*?$/))this.value=this.t_value;elsethis.tvalue=this.value;if(this.value.match(/^(?:[\+\-]?\d+(?:\.\d+)?)?$/))this.ovalue=this.value"onkeyup="if(!this.value.match(/^[\+\-]?\d*?\.?\d*?$/))this.value=this.t_value;elsethis.tvalue=this.value;if(this.value.match(/^(?:[\+\-]?\d+(?:\.\d+)?)?$/))this.ovalue=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.ovalue=this.value}">

4.只能输入字母和汉字
<inputonkeyup="value=value.replace(/[\d]/g,'')"onbeforepaste="clipboardData.setData('text',clipboardData.getData('text').replace(/[\d]/g,''))"maxlength=10name="Numbers">

5.只能输入英文字母和数字,不能输入中文
<inputonkeyup="value=value.replace(/[^\w\.\/]/ig,'')">

6.只能输入数字和英文<fontcolor="Red">chun</font>
<inputonKeyUp="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:
<inputonKeyPress="if((event.keyCode<48||event.keyCode>57)&&event.keyCode!=46||/\.\d\d$/.test(value))event.returnValue=false">

8.小数点后只能有最多两位(数字,字母,可以输入运算符号:
<inputonkeyup="this.value=this.value.replace(/^(\-)*(\d+)\.(\d\d).*$/,'$1$2.$3')">