JavaScript Tips #5 : Important Tips for Using JavaScript

Tip #1 : <script> tag is used to include JavaScript

We can use <script> tag inside HTML statement to include your JavaScript Statement to include in a webpage.

<script>
// All Your Javascript Code goes
//         between the opening and closing
//                  script tags.
</script>

Tip #2 : <script> tag can be placed inside <head> or <body>

  1. Ideally we place JS code inside <head> tag. but there is no such rule which state the position of the <script> tag in HTML document.
  2. JS Code Written outside the JS method will be rendered and can affect the rendering of the page.
<html>
    <head>
        <script type="text/javascript">
            document.write("<p>" + Date() + "</p>");
        </script>
    </head>
    <body>
        <script type="text/javascript">
            document.write("<p>" + Date() + "</p>");
        </script>
    </body>
</html>

will print following output on the screen -

Tue Nov 01 2012 7:15:35 GMT+0530 (India Standard Time)
Tue Nov 01 2012 7:15:35 GMT+0530 (India Standard Time)

Tip #3 : Complete JS code can be combination of JS code from head and body

<html>
    <head>
        <script type="text/javascript">
            var num1 = 10 + 20;
        </script>
    </head>
    <body>
        <script type="text/javascript">
            document.write("<p>" + num1 + "</p>");
        </script>
    </body>
</html>

Tip #4 : Src Attribute may have Relative Path

We can specify relative path to the “src” attribute of the <script> tag. Script tag with src attribute specify that the JS code is present at different source.

<script src="path/sample.js"></script>

Or by specifying absolute path -

<script src="http://wwww.xyz.com/js/sample.js"></script>