How to label a block in JavaScript?

Javascript Web Development Front End Technology

A block statement groups zero or more statements. In languages other than JavaScript, it is known as a compound statement.

Syntax

Here’s the syntax −

{
   //List of statements
}

To add a label to a block, use the following −

Identifier_for_label: {
   StatementList
}

Let’s use it for break statement. You can try to run the following code to use labels to control the flow, with break statement

Example

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>

Ramu Prasad

Updated on: 15-Jun-2020

257 Views

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