Is there a way to break from nested loops in Javascript?
//Write the links to the page. for (var x = 0; x < 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("<a href=\"" + Navigation.Headings[Heading][Item].URL + "\">" + Navigation.Headings[Heading][Item].Name + "</a> : "); break; // <---HERE, I need to break out of two loops. } } } } 
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.
continue and break.CommentedNov 12, 2015 at 21:17Wrap that up in a function and then just return.
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 > 0; x--) { for (var y = Set2.length; y > 0; y--) { for (var z = Set3.length; z > 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.
break or continue immediately after you set z and y? I do like the idea of using the for loop's conditions to kick out. Elegant in its own way.CommentedDec 7, 2015 at 18:01for(var a in b){...} or for(var a of b){...} style for loops.CommentedNov 10, 2019 at 4:36I 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 < 10 && !abort; a++) { for (b = 0; b < 10 && !abort; b++) { if (condition) { doSomeThing(); abort = true; } } } 
condition evaluates to true on the first iteration of the nested loop, you still run through the rest of the 10 iterations, checking the abort value each time. This is not a performance problem for 10 iterations, but it would be with, say, 10,000.abort and the expression. In simple scenarios that might be fine, but for huge loops with gazillion iterations that could be a problemCommentedDec 11, 2017 at 17:08for(var a in b){...} or for(var a of b){...} style for loops.CommentedNov 10, 2019 at 4:38Quite 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; } 
loop1=loop2=false;CommentedApr 9, 2015 at 4:30break 2; like in php.Here are five ways to break out of nested loops in JavaScript:
1) Set parent(s) loop to the end
for (i = 0; i < 5; i++) { for (j = 0; j < 5; j++) { if (j === 2) { i = 5; break; } } } 2) Use label
exit_loops: for (i = 0; i < 5; i++) { for (j = 0; j < 5; j++) { if (j === 2) break exit_loops; } } 3) Use variable
var exit_loops = false; for (i = 0; i < 5; i++) { for (j = 0; j < 5; j++) { if (j === 2) { exit_loops = true; break; } } if (exit_loops) break; } 4) Use self executing function
(function() { for (i = 0; i < 5; i++) { for (j = 0; j < 5; j++) { if (j === 2) return; } } })(); 5) Use regular function
function nested_loops() { for (i = 0; i < 5; i++) { for (j = 0; j < 5; j++) { if (j === 2) return; } } } nested_loops(); 
break 2; like we have in PHP. No loop labels, no functions, no if-else checks, no tempering with / blasting of loop variables - just clean syntax!CommentedNov 10, 2019 at 6:03break 2; does not exist in JS yet, so how could it introduce bugs? You want to label the loops manually? Sure, go ahead - I never said you shouldn't. Also, I in no way advised to manually label JS loops with 3,2,1 - JS does not allow manual labelling of loops with just numbers as of now. I only wished such a thing was implicitly available. Also, such a statement has been a core part of some very popular languages like PHP, and I haven't come across (m)any posts that "want to label the PHP loops manually because break 2; was hard to re-structure".CommentedJan 11, 2021 at 7:31var str = ""; for (var x = 0; x < 3; x++) { (function() { // here's an anonymous function for (var y = 0; y < 3; y++) { for (var z = 0; z < 3; z++) { // you have access to 'x' because of closures str += "x=" + x + " y=" + y + " z=" + z + "<br />"; if (x == z && z == 2) { return; } } } })(); // here, you execute your anonymous function } How's that? :)
x, if any logic within the loop references x at a later point in time (for example it defines an inner anonymous function that is saved and executed later), the value for x will be whatever it was at the end of the loop, not the index that function was defined during. (cont'd)x as a parameter to your anonymous function so that it creates a new copy of it, which can then be referenced as a closure since it won't change from that point on. In short, I recommend ephemient's 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 < 10; i++) { for (var j = 0; j < 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 < 89; i++) { for (var j = 0; j < 1002; j++) { for (var k = 0; k < 16; k++) { for (var l = 0; l < 2382; l++) { if (condition) { console.log("condition met"); i = j = k = l = Number.MAX_VALUE; // Blast the loop variables } } } } } 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) { } python, since exceptions are usually costly JS loop increment + ~75%. If readable enough, I guess it's okay for non-libraries.If you use Coffeescript, there is a convenient "do" keyword that makes it easier to define and immediately execute an anonymous function:
do -> 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.
for loops not two.CommentedJul 19, 2017 at 20:23I 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 = ("<a href=\"" + Navigation.Headings[Heading][Item].URL + "\">" + Navigation.Headings[Heading][Item].Name + "</a> : "); 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("<a href=\"" + Navigation.Headings[Heading][Item].URL + "\">" + Navigation.Headings[Heading][Item].Name + "</a> : "); remainingArgs.splice(i, 1); if (remainingArgs.length === 0) return true; } }); }); How about pushing loops to their end limits
for(var a=0; a<data_a.length; a++){ for(var b=0; b<data_b.length; b++){ for(var c=0; c<data_c.length; c++){ for(var d=0; d<data_d.length; d++){ a = data_a.length; b = data_b.length; c = data_b.length; d = data_d.length; } } } } 
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 < _table.length; i++) { var r = _table[i]; if (!CriteriaMatch(r[i], criteria)) continue; result.add(r); } Hmmm hi to the 10 years old party ?
Why not put some condition in your for ?
var condition = true for (var i = 0 ; i < Args.length && condition ; i++) { for (var j = 0 ; j < Args[i].length && 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) => { return listObj.some((obj) => { return !(obj == "[condition]") }) }) Like this, the loop stopped right after the condition is met
Reminder : This code run in TypeScript
Assign the values which are in comparison condition
function test(){ for(var i=0;i<10;i++) { for(var j=0;j<10;j++) { if(somecondition) { //code to Break out of both loops here i=10; j=10; } } } //Continue from here }
for .. of, close to the example further up which checks for the abort condition:test() function test() { var arr = [1, 2, 3,] var abort = false; for (var elem of arr) { console.log(1, elem) for (var elem2 of arr) { if (elem2 == 2) abort = true; if (!abort) { console.log(2, elem2) } } } } 1 1 2 1 1 2 1 3 
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; }; 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.
