21.预处理指令1-宏定义

/**
* 四舍五入，保留位数为
* @param numberRound
*/
function roundFun(numberRound,roundDigit){   //四舍五入，保留位数为roundDigit
if (numberRound>=0){
var tempNumber = parseInt((numberRound * Math.pow(10,roundDigit)+0.5))/Math.pow(10,roundDigit);
return tempNumber;
}else{
numberRound1 = -numberRound
var tempNumber = parseInt((numberRound1 * Math.pow(10,roundDigit)+0.5))/Math.pow(10,roundDigit);
return -tempNumber;
}
}