题解 | #判断是否符合 USD 格式#

function isUSD(str) {
  let rep = /^\$/,flag = "true",ic=0
        if(!rep.test(str)){
            flag = "false"
        }
        let arr = str.split(",")
        arr.map(e=>{
            if(e.indexOf("$")==-1){
                if(e.indexOf(".")!=-1){
                    e.split(".")[1].length!=2?flag ="false":""
                    e.split(".")[0].length!=3?flag ="false":""
                }else if(e.length!=3){
                    flag ="false"
                }
            }else if(e.length>1){
                ic++
            }
        })
        if(ic!=1){
            flag = "false"
        }
        return flag
}