input输入框输入金额，限制只能输入正数且保留两位小数

<input type="text" οnkeyup="value=value.replace(/[^\d{1,}\.\d{1,}|\d{1,}]/g,'').replace('.','$#$').replace(/\./g,'').replace('$#$','.').replace(/\.{2,}/g,'.').replace(/^(\-)*(\d+)\.(\d\d).*$/,'$1$2.$3')"  maxlength='20'  />