Label in Javascript

While working with loops you might come across a situation where you want to exit a loop. Of course you can use break and continue statement to achieve this.But if you have multi level loops i.e loop within loop, and you want to exit through the outer level loop?.Break and continue statements are used to exit the current loop only , and let me tell you javascript do not have goto statement. Here comes Label to rescue.

Label statement works as an identifier to identify a loop.You can use label statement with break and continue to break or continue the execution.We can create a label by using label name followed by colon.
Syntax
nameofthelabel:

A working example always speaks better than theoretical definition.So lets understand with an example.

var x, y;

outerloop: // label named as outerloop
for (x = 0; x < 4; x++) 
{
    innerloop: // label named as innerloop
    for (y = 0; y < 3; y++) 
    {
       if (x == 1 && y == 1)
          continue innerloop;

       if (x == 2 && y == 2)
          continue outerloop;


       console.log('x = ' + x + ', y = ' + y);
     }
}

Output of the above script would be as follows.

x = 0, y = 0
x = 0, y = 1
x = 0, y = 2
x = 1, y = 0
x = 1, y = 2
x = 2, y = 0
x = 2, y = 1
x = 3, y = 0
x = 3, y = 1
x = 3, y = 2

As you can see x=1, y=1 and x=2 ,y=2 output is missing in the output.
In the script i have labelled outer loop as outerloop and inner loop as innerloop.

if (x == 1 && y == 1)
   continue innerloop;

Here when x and y equals to 1 we stopped the further execution and continued the innerloop using “continue innerloop” statement.That is why we do not see x=1,y=1 in the output.

if (x == 2 && y == 2)
   continue outerloop;

Here when x and y equals to 2 we stopped the further execution and continued the outerloop using “continue outerloop” statement.That is why we do not see x=2,y=2 in the output.

 

I hope using above example i have explained how label works.You can also use break statement .