Browsers that do not support Javascript, will display Javascript as page content.
To prevent them from doing this and as a part of the Javascript standard the HTML comment tag should be used to "hide" the javascript.
Just add an HTML comment tag <!-- before the first Javascript statement and a --> (end of comment) after the last Javascript statement, like this:
<html>
<body>
<script type="text/javascript">
<!--
document.getElementById("demo").innerHTML=Date();
//-->
</script>
</body>
</html>
The two forward slashes at the end of the comment line (//) is the Javascript comment symbol. This prevents Javascript from executing the --> tag.
Warning for non-Javascript browsers:
If you have to do something important using Javascript then you can display a warning message to the user using <noscript> tags.
You can add a noscript block immediately after the script block as follows:
<html>
<body>
<script language="javascript" type="text/javascript">
<!--
document.write("Hello World!")
//-->
</script>
<noscript>
Sorry...Javascript is needed to go ahead.
</noscript>
</body>
</html>
Now, if user's browser does not support Javascript or Javascript is not enabled then message from </noscript> will be displayed on the screen.
Semicolons are optional:
Simple statements in javascript are generally followed by a semicolon character, just as they are in C,C++, and Java. Javascript, however allows you to omit this semicolon if your statements are each placed on a separate line. For example, the following code could be written without semicolons.
<script language="javascript" type="text/javascsript">
<!--
var1 = 10
var2 = 20
//-->
</script>
But when formatted in a single line as follows, the semicolons are required:
<script language="javascript" type="text/javascript">
<!--
var1 = 10; var2 = 20;
//-->
</script>
Note: It is a good programming practice to use semicolons.
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