js input 数字后面是两位小数点

二者任选其一

1.   //直接Input可以完成需求

<input type = "text" name= "price" id = 'price' onkeyup= "if( ! /^-?\d+\.?\d{0,2}$/.test(this.value)){ var s = this.value;this.value=s.substring(0,s.indexOf('.')+3)}" />


2.   //Input +js 可以完成需求
<input type = "text" name= "price" id = 'price' onkeyup= "keyup($(this));" />
<script src="https://cdn.bootcss.com/jquery/2.0.0/jquery.min.js"></script>
<script>


function keyup(that){
var s = that.val();
if( ! /^-?\d+\.?\d{0,2}$/.test(s)){ 
that.value=s.substring(0,s.indexOf(".")+3);
}
}
</script>