//match()
var str = "中国移动10086,中国联通10010,中国电信10000";
let arr = str.match(/\d{5}/g)//10086 10010 10000

//replace()
let str="盈十里煌绸 交 错"
str.replace(/\s/g,"")//盈十里煌绸交错

//test()
let res=/\d{5}/;
res.test("我投你猴:1456")//false

//exec()
let str = "中国移动10086,中国联通10010,中国电信10000";
var reg=/\d{5}/g;
reg.exec(str) //10086
reg.exec(str)  //10010