How to break nested loops in JavaScript

Question

I tried this   for i   0  i  lt  5  i         for j   i   1  j  lt  5  j             break 2             alert 1       only to get      SyntaxError  missing   before statement   So  how would I break a nested loop in JavaScript

User · Answer

Unfortunately you ll have to set a flag or use labels  think old school goto statements   var breakout   false   for i 0 i lt 5 i          for j i 1 j lt 5 j                  breakout   true          break            if  breakout  break      alert 1       The label approach looks like   end loops  for i 0 i lt 5 i          for j i 1 j lt 5 j                  break end loops            alert 1       edit  label incorrectly placed   also see    http   www devguru com Technologies ecmascript quickref break html http   www daaq net old javascript index php page js exiting loops amp parent js statements

User · Answer

There are at least five different ways to break out of two or more loops   1  Set parent s  loop to the end  for  i   0  i  lt  5  i          for  j   0  j  lt  5  j                  if  j     2                        i   5              break                      2  Use label  fast  for  i   0  i  lt  5  i          for  j   0  j  lt  5  j                  if  j     2              break fast            3  Use variable  var exit loops   false  for  i   0  i  lt  5  i          for  j   0  j  lt  5  j                  if  j     2                        exit loops   true              break                      if  exit loops          break      4  Use self executing function   function         for  i   0  i  lt  5  i                  for  j   0  j  lt  5  j                           if  j     2                   return                          5  Use regular function  function nested loops         for  i   0  i  lt  5  i                  for  j   0  j  lt  5  j                           if  j     2                   return                    nested loops

User · Answer

The another trick is by setting the parent loop to reach the end and then break the current loop  function foo         for var k   0  k  lt  4  k             for var m   0  m  lt  4  m                 if m    2                   k   5     Set this then break                 break                          console log m

User · Answer

You need to name your outer loop and break that loop  rather than your inner loop - like this   outer loop   for i 0 i lt 5 i          for j i 1 j lt 5 j              break outer loop            alert 1

User · Answer

Break 1st loop   for i 0 i lt 5 i        for j i 1 j lt 5 j              do something      break        alert 1        Break both loops   for i 0 i lt 5 i        var breakagain   false    for j i 1 j lt 5 j              do something      breakagain   true      break        alert 1     if breakagain      break

User · Answer

break doesn t take parameters  There are two workarounds    Wrap them in a function and call return Set a flag in the inner loop and break again right after the loop if the flag is set

User · Answer

Wrap in a self executing function and return   function        for i 0 i lt 5 i             for  j 0 j lt 3 j                   console log i     j               if  j    2  return

User · Answer

In my opinion  it s important to keep your construct vocabulary to a minimum  If I can do away with breaks and continues easily  I do so   function foo          var found   false      for var k   0   k  lt  4  amp  amp   found   k             for var m   0   m  lt  4  amp  amp   found   m                if  m     2                  found   true                                   return found      Be warned  after the loop  m and k are one larger that you might think  This is because m   and k   are executed before their loop conditions  However  it s still better than  dirty  breaks   EDIT  long comment  Dennis     I wasn t being 100  serious about being  dirty   but I still think that  break  contravenes my own conception of clean code  The thought of having multi-level breaks actually makes me feel like taking a shower   I find justifying what I mean about a feeling about code because I have coded all life  The best why I can think of it is is a combination of manners and grammar  Breaks just aren t polite  Multi level breaks are just plain rude   When looking at a for statement  a reader knows exactly where to look  Everything you need to know about the rules of engagement are in the contract  in between the parenthesis  As a reader  breaks insult me  it feels like I ve been cheated upon   Clarity is much more respectful than cheating

User · Answer

You can break nested for loops with the word  break   it works without any labels    In your case you need to have a condition which is sufficient to break a loop   Here s an example   var arr     1 3    5 6    9 10    for  var a   0  a lt arr length  a        for  var i 0  i lt arr a  length  i          console log  I am a nested loop and i       i       if  i  0    break          console log  first loop continues        It logs the following    gt  I am a nested loop and i   0   gt  first loop continues  gt  I am a nested loop and i   0   gt  first loop continues  gt  I am a nested loop and i   0   gt  first loop continues   The return  statement does not work in this case  Working pen

User · Answer

loop1      for  var i in set1    loop2          for  var j in set2    loop3              for  var k in set3                    break loop2      breaks out of loop3 and loop2                                 code copied from Best way to break from nested loops in Javascript   Please search before posting a question   The link was the FIRST related question I saw on the left side of this page

User · Answer

You should be able to break to a label  like so   function foo          dance      for var k   0  k  lt  4  k             for var m   0  m  lt  4  m                 if m    2                   break dance

User · Answer

function myFunction      for var i   0 i  lt  n i         for var m   0 m  lt  n m           if   break condition             goto out                    out     your out of the loop

User · Answer

You return to  break  you nested for loop   function foo            dance      for var k   0  k  lt  4  k             for var m   0  m  lt  4  m                 if m    2                     break dance                  return                                  foo

User · Answer

See Aaron s  Otherwise  j 5 i 5 instead of break

User · Answer

Use function for multilevel loops - this is good way   function find dup          for                for                   if  done  return

[javascript] How to break nested loops in JavaScript?

Examples related to javascript

Examples related to nested-loops

Examples related to break