https://github.com/Tencent/vConsole/blob/dev/src/lib/query.js#L142
https://www.cnblogs.com/hjbky/p/6178625.html
https://www.jb51.net/article/100027.htm
主要作用是跳出多重循环。
var num = 0;outPoint: for (var i = 0; i < 10; i++) { for (var j = 0; j < 10; j++) { if (i == 5 && j == 5) { break outPoint; } num++; } }alert(num); // 55