JS判斷只能是數(shù)字和小數(shù)點(diǎn) 

1.文本框只能輸入數(shù)字代碼(小數(shù)點(diǎn)也不能輸入) 
<input onkeyup="this.value=this.value.replace(/\D/g,'')" onafterpaste="this.value=this.value.replace(/\D/g,'')"> 

2.只能輸入數(shù)字,能輸小數(shù)點(diǎn). 
<input onkeyup="if(isNaN(value))execCommand('undo')" onafterpaste="if(isNaN(value))execCommand('undo')"> 
<input name=txt1 onchange="if(/\D/.test(this.value)){alert('只能輸入數(shù)字');this.value='';}"> 

3.數(shù)字和小數(shù)點(diǎn)方法二 
<input type=text tvalue="" ovalue="" onkeypress="if(!this.value.match(/^[\+\-]?\d*?\.?\d*?$/))this.value=this.t_value;else this.tvalue=this.value;if(this.value.match(/^(?:[\+\-]?\d+(?:\.\d+)?)?$/))this.ovalue=this.value" onkeyup="if(!this.value.match(/^[\+\-]?\d*?\.?\d*?$/))this.value=this.t_value;else this.tvalue=this.value;if(this.value.match(/^(?:[\+\-]?\d+(?:\.\d+)?)?$/))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.只能輸入字母和漢字 
<input onkeyup="value=value.replace(/[\d]/g,'') "onbeforepaste="clipboardData.setData('text',clipboardData.getData('text').replace(/[\d]/g,''))" maxlength=10 name="Numbers"> 

5.只能輸入英文字母和數(shù)字,不能輸入中文 
<input onkeyup="value=value.replace(/[^\w\.\/]/ig,'')"> 

6.只能輸入數(shù)字和英文<font color="Red">chun</font> 
<input onKeyUp="value=value.replace(/[^\d|chun]/g,'')"> 

7.小數(shù)點(diǎn)后只能有最多兩位(數(shù)字,中文都可輸入),不能輸入字母和運(yùn)算符號(hào): 
<input onKeyPress="if((event.keyCode<48 || event.keyCode>57) && event.keyCode!=46 || /\.\d\d$/.test(value))event.returnValue=false"> 

8.小數(shù)點(diǎn)后只能有最多兩位(數(shù)字,字母,中文都可輸入),可以輸入運(yùn)算符號(hào): 
<input onkeyup="this.value=this.value.replace(/^(\-)*(\d+)\.(\d\d).*$/,'$1$2.$3')"> 

只能是數(shù)字和小數(shù)點(diǎn)和加減乘際

onkeypress="return event.keyCode>=4&&event.keyCode<=57"