从 Javascript 中的 switch case 内部中断 for 循环

Break for loop from inside of switch case in Javascript

提问by BASILIO

What command I must use, to get out of the for loop, also from //code insidejump direct to //code after

我必须使用什么命令才能退出 for 循环，也可以从//code inside直接跳转到//code after

//code before
for(var a in b)
    {
    switch(something)
        {
        case something:
            {
            //code inside
            break;
            }
        }
    }
//code after

采纳答案by lonesomeday

Unfortunately, Javascript doesn't have allow breaking through multiple levels. The easiest way to do this is to leverage the power of the returnstatement by creating an anonymous function:

不幸的是，Javascript 不允许break通过多个级别。最简单的方法是return通过创建匿名函数来利用语句的强大功能：

//code before
(function () {
    for (var a in b) {
        switch (something) {
        case something:
            {
                //code inside
                return;
            }
        }
    }
}());
//code after

This works because returnleaves the function and therefore implicitly leaves the loop, moving you straight to code after

这是有效的，因为return离开了函数，因此隐式地离开了循环，让你直接进入code after

回答by Brad Christie

use another variable to flag when you need to exit:

需要退出时使用另一个变量来标记：

var b = { firstName: 'Peter', lastName: 'Smith' };
var keepGoing = true;
for (var a in b) {
  switch (true) {
    case 1:
      keepGoing = false;
      break;
  }
  if (!keepGoing) break;
  console.log('switch end');
}
console.log('for end');

example

例子

回答by Chubby Boy

You can use label. Have a labeled statement and break to that label. outerLoopis the label I have used here.

您可以使用label. 有一个带标签的声明并打破该标签。outerLoop是我在这里使用的标签。

//code before
outerLoop:
for (var a in b) {
    switch (something) {
        case 'case1':
            //code inside
            break outerLoop;
    }
}
//code after

回答by Jeff

it depends on what you want to accomplish... one thing I commonly do is something like this:

这取决于你想完成什么......我经常做的一件事是这样的：

    //code before
for(var a in b)
{
    var breakFor = false;
    switch(something)
    {
        case something:
        {
            //code inside
            breakFor = true;
            break;
        }
    }
    if (breakFor)
        break;
}
//code after

回答by Skarlinski

You can tell which loop / switch to break.

您可以判断要中断哪个循环/开关。

function foo ()
{
    dance:
    for(var k = 0; k < 4; k++){
        for(var m = 0; m < 4; m++){
            if(m == 2){
                break dance;
            }
        }
    }
}

See this answer.

看到这个答案。

回答by gest

for(var i=0; i<b.length; i++) {
   switch (something) {
       case 'something1':
           i=b.length;
   }
}

When the iteration variable ireaches the end of the loop, it breaks. But one can force the iteration variable to reach the end of the loop.

当迭代变量i到达循环末尾时，它会中断。但是可以强制迭代变量到达循环的末尾。

回答by Andrew_CS

I always find using conditional statements one of the easiest ways to control the code flow, at least conceptually.

我总是发现使用条件语句是控制代码流的最简单方法之一，至少在概念上是这样。

var done = false;
//code before for loop
for(var a in b){
    switch(switchParameter){
        case firstCase:
            //code inside
            done = true;
            break;
        }
    }
    if(done)
        break;
}
//code outside of for loop