JavaScript Comments

From http://www.w3schools.com (Copyright Refsnes Data)

# JavaScript Comments

JavaScript comments can be used to make the code more readable.

## JavaScript Comments

Comments can be added to explain the JavaScript, or to make it more readable.

Single line comments start with //.

This example uses single line comments to explain the code:

    <script type="text/javascript">
    // This will write a header:
    document.write("<h1>This is a header</h1>");
    // This will write two paragraphs:
    document.write("<p>This is a paragraph</p>");
    document.write("<p>This is another paragraph</p>");
    </script>

Try it yourself.

## JavaScript Multi-Line Comments

Multi line comments start with /* and end with */.

This example uses a multi line comment to explain the code:

    <script type="text/javascript">
    /*
    The code below will write
    one header and two paragraphs
    */
    document.write("<h1>This is a header</h1>");
    document.write("<p>This is a paragraph</p>");
    document.write("<p>This is another paragraph</p>");
    </script>

Try it yourself.

## Using Comments to Prevent Execution

In this example the comment is used to prevent the execution of a single code line:

    <script type="text/javascript">
    document.write("<h1>This is a header</h1>");
    document.write("<p>This is a paragraph</p>");
    //document.write("<p>This is another paragraph</p>");
    </script>

Try it yourself.

In this example the comments is used to prevent the execution of multiple code lines:

    <script type="text/javascript">
    /*
    document.write("<h1>This is a header</h1>");
    document.write("<p>This is a paragraph</p>");
    document.write("<p>This is another paragraph</p>");
    */
    </script>

Try it yourself.

## Using Comments at the End of a Line

In this example the comment is placed at the end of a line:

    <script type="text/javascript">
    document.write("Hello"); // This will write "Hello"
    document.write("Dolly"); // This will write "Dolly"
    </script>

From http://www.w3schools.com (Copyright Refsnes Data)