javascript - JS 这个循环是什么 :/break loop notation?

Question

我刚看到这段代码:

    var indx, hash;
    loop:
    for (var i in config.users) {
        if (config.users[i].email === dataValues.email) {
            indx = i;
            hash = config.users[i].hash;
            break loop;
        }
    }

这是有效的代码吗？什么是“循环:”？如果不看到常规的 for .. in/while 循环，就很难用谷歌搜索“js loop:”

Answer 1

是的，这个有效代码。

loop 这里是label

The labeled statement can be used with break or continue statements. It is prefixing a statement with an identifier which you can refer to.

注意 JavaScript 没有NO goto 语句，您只能使用带有break 或continue 的标签。

var i, j;

loop1:
for (i = 0; i < 3; i++) {      //The first for statement is labeled "loop1"
   loop2:
   for (j = 0; j < 3; j++) {   //The second for statement is labeled "loop2"
      if (i === 1 && j === 1) {
         break loop1;
      }
      document.write("i = " + i + ", j = " + j + "<br />");
   }
}