如下所示：
regexNum (num) {
var re =/(-?\d+)(\d{3})/
if(/^.*\..*$/.test(num)){
var pointIndex =num.lastIndexOf(".")
var intPart = num.substring(0, pointIndex)
var pointPart =num.substring(pointIndex+1, num.length)
intPart = intPart +"";
while(re.test(intPart)){
intPart =intPart.replace(re,"$1,$2")
}
num = intPart+"."+pointPart
}else{
num = num +"";
while(re.test(num)){
num =num.replace(re,"$1,$2")
}
}
return num
}
