Break for loop from inside of switch case in Javascript

问题

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

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

回答1:

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

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

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

回答2:

use another variable to flag when you need to exit:

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

回答3:

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

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

回答4:

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

    //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5:

You can tell which loop / switch to break.

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.

回答6:

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

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

回答7:

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

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

来源：https://stackoverflow.com/questions/17072605/break-for-loop-from-inside-of-switch-case-in-javascript