Break for loop from inside of switch case in Javascript

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被撕碎了的回忆 2020-12-16 10:09

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         


        
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  • 2020-12-16 10:46

    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


    As pointed out in the comments, my above answer is incorrect and it is possible to multi-level breaking, as in Chubby Boy's answer, which I have upvoted.

    Whether this is wise is, from a seven-year-later perspective, somewhat questionable.

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  • 2020-12-16 10:47
    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.

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  • 2020-12-16 10:52

    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
    
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  • 2020-12-16 10:57

    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

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  • 2020-12-16 11:03

    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
    
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  • 2020-12-16 11:04

    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.

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