Learn How to Hiding JavaScript Statements , Lesson 10
HTML comments begin with the characters <!– and end with –>. The browser knows not to display anything between these sets of characters. You also know that the HTML <SCRIPT> tag is used to embed JavaScript into HTML pages. Both JavaScript and non-JavaScript browsers know not to display the <SCRIPT> tags.
However, non-JavaScript browsers do not know what to make of the statements within the <SCRIPT> tags, so they will display the actual lines of the script right in the middle of the HTML page. I am sure that this is not what you want your visitors to see. To get around this unsightly mess, you can enclose all the JavaScript statements starting after the beginning <SCRIPT> tag and before the ending </SCRIPT> tag within HTML comments, as demonstrated in the following example:
<HTML>
<HEAD>
<TITLE>Script 2.1 -Example of Comment Statements</TITLE>
</HEAD>
<BODY>
<SCRIPT LANGUAGE=”JavaScript” TYPE=”Text/JavaScript”>
<!– Start hiding JavaScript statements
document.write(“Non-JavaScript browsers will not see
this message.”);
// End hiding JavaScript statements –>
</SCRIPT>
</BODY>
</HTML>
Since browsers are smart enough not to process any HTML that they do not understand, the starting and ending <SCRIPT> tags are ignored by non-JavaScript browsers. At the same time, non-JavaScript browsers will view everything between the HTML comments tags as one big comment and ignore it, thus hiding all JavaScript statements and preventing their display.
JavaScript-enabled browsers, on the other hand, will recognize the starting and ending <SCRIPT> tags and process them accordingly. These browsers also will recognize the opening HTML comment tag and ignore it, while simultaneously seeing the line beginning with the // characters as a JavaScript comment and ignoring it as well.
You also can use comments to make your JavaScripts and JScripts self-documenting by using them to add descriptive comments to your scripts.
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