保留带负数的两位小数

//带负数保留两位小数
function clearNoNum(obj) {
    obj.value = obj.value.replace(/[^\d.-]/g,""); //清除"数字"和"."和"-"以外的字符
    obj.value = obj.value.replace(/^[^-|\d]{1}/g,""); //只能以"-"和数字开头
    obj.value = obj.value.replace(/([\d.-])(-)/g,"$1"); //清除"数字"或"."或"-" 后面的"-"
    obj.value = obj.value.replace(/(-)(\.)/g,"$1"); //清除"-" 后面的"."
    obj.value = obj.value.replace(".","$#$").replace(/\./g,"").replace("$#$",".");//只保留一个"."
    obj.value = obj.value.replace(/^(\-)*(\d+)\.(\d\d).*$/,'$1$2.$3'); //只能输入两个小数
				
}
//如果末尾为"."，则失去焦点后清除小数点
function clearDot(obj) {
    obj.value = obj.value.replace(/\.$/g,""); //如果末尾没有数值则清除末尾的"."			
}

<input type="text"  onkeyup="clearNoNum(this)" onblur="clearDot(obj)" >