What are label statements in JavaScript?

Javascript Web Development Front End Technology

JavaScript label statements are used to prefix a label to an identifier. A label can be used with break and continue statement to control the flow more precisely. A label is simply an identifier followed by a colon (:) that is applied to a statement or a block of code. We will see two different examples to understand how to use labels with break and continue.

Example

You can try to run the following code to use labels to control the flow, with break statement

Live Demo

<html>
   <body>
      <script>
         document.write("Entering the loop!<br /> ");

         outerloop: // This is the label name
            for (var i = 0; i < 5; i++) {
               document.write("Outerloop: " + i + "<br />");

               innerloop:
                  for (var j = 0; j < 5; j++) {
                     if (j > 3 ) break ; // Quit the innermost loop
                     if (i == 2) break innerloop; // Do the same thing
                     if (i == 4) break outerloop; // Quit the outer loop
                     document.write("Innerloop: " + j + " <br />");
                  }
            }
            document.write("Exiting the loop!<br /> ");
      </script>
   </body>
</html>

Example

You can try to run the following code to use labels to control the flow, with continue statement

Live Demo

<html>
   <body>
      <script>
         document.write("Entering the loop!<br /> ");
 
         outerloop: // This is the label name
         for (var i = 0; i < 3; i++) {
            document.write("Outerloop: " + i + "<br />");
            for (var j = 0; j < 5; j++) {
               if (j == 3) {
                  continue outerloop;
               }
               document.write("Innerloop: " + j + "<br />");
            }
         }
         document.write("Exiting the loop!<br /> ");
      </script>
   </body>
</html>

Karthikeya Boyini

Published on 08-Feb-2018 06:37:46

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