What s the best way to break from nested loops in JavaScript

Question

What s the best way to break from nested loops in Javascript     Write the links to the page  for  var x   0  x  lt  Args length  x         for  var Heading in Navigation Headings             for  var Item in Navigation Headings Heading                    if  Args x     Navigation Headings Heading  Item  Name                         document write   lt a href                       Navigation Headings Heading  Item  URL       gt                     Navigation Headings Heading  Item  Name     lt  a gt                    break      lt ---HERE  I need to break out of two loops

User · Answer

Already mentioned previously by swilliams  but with an example below  Javascript       Function wrapping inner for loop function CriteriaMatch record  criteria      for  var k in criteria        if    k in record         return false       if  record k     criteria k         return false         return true        Outer for loop implementing continue if inner for loop returns false var result        for  var i   0  i  lt   table length  i        var r    table i      if   CriteriaMatch r i   criteria       continue     result add r

User · Answer

XXX Validation   function         var ok   false  loop      do           for                     while                         if                             break loop     Exist the outermost do-while loop                                   if                             continue     skips current iteration in the while loop                                                   if                     break loop                    if                     break loop                    if                     break loop                    if                     break loop                    ok   true          break        while true       CleanupAndCallbackBeforeReturning ok       return ok

User · Answer

I realize this is a really old topic  but since my standard approach is not here yet  I thought I post it for the future googlers   var a  b  abort   false  for  a   0  a  lt  10  amp  amp   abort  a          for  b   0  b  lt  10  amp  amp   abort  b              if  condition                doSomeThing                abort   true

User · Answer

Wrap that up in a function and then just return

User · Answer

How about pushing loops to their end limits      for var a 0  a lt data a length  a            for var b 0  b lt data b length  b                for var c 0  c lt data c length  c                   for var d 0  d lt data d length  d                      a    data a length                   b    data b length                   c    data b length                   d    data d length

User · Answer

I thought I d show a functional-programming approach  You can break out of nested Array prototype some   and or Array prototype every   functions  as in my solutions  An added benefit of this approach is that Object keys   enumerates only an object s own enumerable properties  whereas   a for-in loop enumerates properties in the prototype chain as well    Close to the OP s solution       Args forEach function  arg               This guard is not necessary             since writing an empty string to document would not change it          if   getAnchorTag arg               return           document write getAnchorTag arg                 function getAnchorTag  name            var res                Object keys Navigation Headings  some function  Heading                return Object keys Navigation Headings Heading   some function  Item                    if  name    Navigation Headings Heading  Item  Name                        res      lt a href                                        Navigation Headings Heading  Item  URL       gt                                      Navigation Headings Heading  Item  Name     lt  a gt                            return true                                                         return res          Solution that reduces iterating over the Headings Items       var remainingArgs   Args slice 0        Object keys Navigation Headings  some function  Heading            return Object keys Navigation Headings Heading   some function  Item                var i   remainingArgs indexOf Navigation Headings Heading  Item  Name                if  i     -1                  return               document write   lt a href                                                Navigation Headings Heading  Item  URL       gt                                              Navigation Headings Heading  Item  Name     lt  a gt                    remainingArgs splice i  1                if  remainingArgs length     0                  return true

User · Answer

If you use Coffeescript  there is a convenient  do  keyword that makes it easier to define and immediately execute an anonymous function   do - gt    for a in first loop     for b in second loop       if condition              return      so you can simply use  return  to get out of the loops

User · Answer

Wrap that up in a function and then just return

User · Answer

How about using no breaks at all  no abort flags  and no extra condition checks  This version just blasts the loop variables  makes them Number MAX VALUE  when the condition is met and forces all the loops to terminate elegantly      No breaks needed for  var i   0  i  lt  10  i        for  var j   0  j  lt  10  j          if  condition          console log  condition met          i   j   Number MAX VALUE     Blast the loop variables               There was a similar-ish answer for decrementing-type nested loops  but this works for incrementing-type nested loops without needing to consider each loop s termination value for simple loops   Another example      No breaks needed for  var i   0  i  lt  89  i        for  var j   0  j  lt  1002  j          for  var k   0  k  lt  16  k            for  var l   0  l  lt  2382  l              if  condition              console log  condition met              i   j   k   l   Number MAX VALUE     Blast the loop variables

User · Answer

Quite simple   var a    1  2  3   var b    4  5  6   var breakCheck1   false   for  var i in a        for  var j in b            breakCheck1   true          break            if  breakCheck1  break

User · Answer

Just like Perl  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                                as defined in EMCA-262 section 12 12   MDN Docs  Unlike C  these labels can only be used for continue and break  as Javascript does not have goto

User · Answer

I realize this is a really old topic  but since my standard approach is not here yet  I thought I post it for the future googlers   var a  b  abort   false  for  a   0  a  lt  10  amp  amp   abort  a          for  b   0  b  lt  10  amp  amp   abort  b              if  condition                doSomeThing                abort   true

User · Answer

Quite simple   var a    1  2  3   var b    4  5  6   var breakCheck1   false   for  var i in a        for  var j in b            breakCheck1   true          break            if  breakCheck1  break

User · Answer

Wrap that up in a function and then just return

User · Answer

I thought I d show a functional-programming approach  You can break out of nested Array prototype some   and or Array prototype every   functions  as in my solutions  An added benefit of this approach is that Object keys   enumerates only an object s own enumerable properties  whereas   a for-in loop enumerates properties in the prototype chain as well    Close to the OP s solution       Args forEach function  arg               This guard is not necessary             since writing an empty string to document would not change it          if   getAnchorTag arg               return           document write getAnchorTag arg                 function getAnchorTag  name            var res                Object keys Navigation Headings  some function  Heading                return Object keys Navigation Headings Heading   some function  Item                    if  name    Navigation Headings Heading  Item  Name                        res      lt a href                                        Navigation Headings Heading  Item  URL       gt                                      Navigation Headings Heading  Item  Name     lt  a gt                            return true                                                         return res          Solution that reduces iterating over the Headings Items       var remainingArgs   Args slice 0        Object keys Navigation Headings  some function  Heading            return Object keys Navigation Headings Heading   some function  Item                var i   remainingArgs indexOf Navigation Headings Heading  Item  Name                if  i     -1                  return               document write   lt a href                                                Navigation Headings Heading  Item  URL       gt                                              Navigation Headings Heading  Item  Name     lt  a gt                    remainingArgs splice i  1                if  remainingArgs length     0                  return true

User · Answer

var str       for  var x   0  x  lt  3  x           function         here s an anonymous function         for  var y   0  y  lt  3  y                  for  var z   0  z  lt  3  z                         you have access to  x  because of closures                 str     x     x      y     y      z     z     lt br   gt                    if  x    z  amp  amp  z    2                        return                                                          here  you execute your anonymous function     How s that

User · Answer

I m a little late to the party but the following is a language-agnostic approach which doesn t use GOTO labels or function wrapping   for  var x   Set1 length  x  gt  0  x--       for  var y   Set2 length  y  gt  0  y--             for  var z   Set3 length  z  gt  0  z--                    z   y   -1     terminates second loop              z   y   x   -1     terminate first loop                  On the upside it flows naturally which should please the non-GOTO crowd  On the downside  the inner loop needs to complete the current iteration before terminating so it might not be applicable in some scenarios

User · Answer

Wrap that up in a function and then just return

User · Answer

There are many excellent solutions above  IMO  if your break conditions are exceptions  you can use try-catch  try        for  var i in set1            for  var j in set2                for  var k in set3                    throw error                                 catch  error

User · Answer

Just like Perl  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                                as defined in EMCA-262 section 12 12   MDN Docs  Unlike C  these labels can only be used for continue and break  as Javascript does not have goto

User · Answer

the best way is - 1  Sort the both array which are used in first and second loop   2  if item matched then break the inner loop and hold the index value  3  when start next iteration start inner loop with hold index value

User · Answer

Hmmm hi to the 10 years old party    Why not put some condition in your for    var condition   true for  var i   0   i  lt  Args length  amp  amp  condition   i          for  var j   0   j  lt  Args i  length  amp  amp  condition   j              if  Args i  obj j       condition                  condition   false                     Like this you stop when you want  In my case  using Typescript  we can use some   which go through the array and stop when condition is met So my code become like this    Args some  listObj    gt        return listObj some  obj    gt            return   obj      condition                Like this  the loop stopped right after the condition is met  Reminder   This code run in TypeScript

User · Answer

Just like Perl  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                                as defined in EMCA-262 section 12 12   MDN Docs  Unlike C  these labels can only be used for continue and break  as Javascript does not have goto

User · Answer

Here are five ways to break out of nested loops in JavaScript   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  exit loops  for  i   0  i  lt  5  i          for  j   0  j  lt  5  j                  if  j     2              break exit loops            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

Already mentioned previously by swilliams  but with an example below  Javascript       Function wrapping inner for loop function CriteriaMatch record  criteria      for  var k in criteria        if    k in record         return false       if  record k     criteria k         return false         return true        Outer for loop implementing continue if inner for loop returns false var result        for  var i   0  i  lt   table length  i        var r    table i      if   CriteriaMatch r i   criteria       continue     result add r

User · Answer

How about pushing loops to their end limits      for var a 0  a lt data a length  a            for var b 0  b lt data b length  b                for var c 0  c lt data c length  c                   for var d 0  d lt data d length  d                      a    data a length                   b    data b length                   c    data b length                   d    data d length

User · Answer

Here are five ways to break out of nested loops in JavaScript   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  exit loops  for  i   0  i  lt  5  i          for  j   0  j  lt  5  j                  if  j     2              break exit loops            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

var str       for  var x   0  x  lt  3  x           function         here s an anonymous function         for  var y   0  y  lt  3  y                  for  var z   0  z  lt  3  z                         you have access to  x  because of closures                 str     x     x      y     y      z     z     lt br   gt                    if  x    z  amp  amp  z    2                        return                                                          here  you execute your anonymous function     How s that

User · Answer

How about using no breaks at all  no abort flags  and no extra condition checks  This version just blasts the loop variables  makes them Number MAX VALUE  when the condition is met and forces all the loops to terminate elegantly      No breaks needed for  var i   0  i  lt  10  i        for  var j   0  j  lt  10  j          if  condition          console log  condition met          i   j   Number MAX VALUE     Blast the loop variables               There was a similar-ish answer for decrementing-type nested loops  but this works for incrementing-type nested loops without needing to consider each loop s termination value for simple loops   Another example      No breaks needed for  var i   0  i  lt  89  i        for  var j   0  j  lt  1002  j          for  var k   0  k  lt  16  k            for  var l   0  l  lt  2382  l              if  condition              console log  condition met              i   j   k   l   Number MAX VALUE     Blast the loop variables

User · Answer

Just like Perl  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                                as defined in EMCA-262 section 12 12   MDN Docs  Unlike C  these labels can only be used for continue and break  as Javascript does not have goto

User · Answer

Hmmm hi to the 10 years old party    Why not put some condition in your for    var condition   true for  var i   0   i  lt  Args length  amp  amp  condition   i          for  var j   0   j  lt  Args i  length  amp  amp  condition   j              if  Args i  obj j       condition                  condition   false                     Like this you stop when you want  In my case  using Typescript  we can use some   which go through the array and stop when condition is met So my code become like this    Args some  listObj    gt        return listObj some  obj    gt            return   obj      condition                Like this  the loop stopped right after the condition is met  Reminder   This code run in TypeScript

User · Answer

var str       for  var x   0  x  lt  3  x           function         here s an anonymous function         for  var y   0  y  lt  3  y                  for  var z   0  z  lt  3  z                         you have access to  x  because of closures                 str     x     x      y     y      z     z     lt br   gt                    if  x    z  amp  amp  z    2                        return                                                          here  you execute your anonymous function     How s that

User · Answer

XXX Validation   function         var ok   false  loop      do           for                     while                         if                             break loop     Exist the outermost do-while loop                                   if                             continue     skips current iteration in the while loop                                                   if                     break loop                    if                     break loop                    if                     break loop                    if                     break loop                    ok   true          break        while true       CleanupAndCallbackBeforeReturning ok       return ok

User · Answer

the best way is - 1  Sort the both array which are used in first and second loop   2  if item matched then break the inner loop and hold the index value  3  when start next iteration start inner loop with hold index value

User · Answer

var str       for  var x   0  x  lt  3  x           function         here s an anonymous function         for  var y   0  y  lt  3  y                  for  var z   0  z  lt  3  z                         you have access to  x  because of closures                 str     x     x      y     y      z     z     lt br   gt                    if  x    z  amp  amp  z    2                        return                                                          here  you execute your anonymous function     How s that

User · Answer

There are many excellent solutions above  IMO  if your break conditions are exceptions  you can use try-catch  try        for  var i in set1            for  var j in set2                for  var k in set3                    throw error                                 catch  error

User · Answer

If you use Coffeescript  there is a convenient  do  keyword that makes it easier to define and immediately execute an anonymous function   do - gt    for a in first loop     for b in second loop       if condition              return      so you can simply use  return  to get out of the loops

User · Answer

I m a little late to the party but the following is a language-agnostic approach which doesn t use GOTO labels or function wrapping   for  var x   Set1 length  x  gt  0  x--       for  var y   Set2 length  y  gt  0  y--             for  var z   Set3 length  z  gt  0  z--                    z   y   -1     terminates second loop              z   y   x   -1     terminate first loop                  On the upside it flows naturally which should please the non-GOTO crowd  On the downside  the inner loop needs to complete the current iteration before terminating so it might not be applicable in some scenarios

[javascript] What's the best way to break from nested loops in JavaScript?

Examples related to javascript

Examples related to loops

Examples related to nested-loops

Examples related to break