标记语句， goto语法的应用

标记语句可以和 break 或 continue 语句一起使用。标记就是在一条语句前面加个可以引用的标识符（identifier）。

https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Statements/label

 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) {
             continue loop1;
          }
          console.log('i = ' + i + ', j = ' + j);
       }
    }

// Output is:
//   "i = 0, j = 0"
//   "i = 0, j = 1"
//   "i = 0, j = 2"
//   "i = 1, j = 0"
//   "i = 2, j = 0"
//   "i = 2, j = 1"
//   "i = 2, j = 2"
// Notice how it skips both "i = 1, j = 1" and "i = 1, j = 2"

　　

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;
      }
      console.log("i = " + i + ", j = " + j);
   }
}

// Output is:
//   "i = 0, j = 0"
//   "i = 0, j = 1"
//   "i = 0, j = 2"
//   "i = 1, j = 0"
// Notice the difference with the previous continue example

　　

foo: {
  console.log('face');
  break foo;
  console.log('this will not be executed');
}
console.log('swap');

// this will log:

// "face"
// "swap