MAKING ONCLICK ALERT

This is an example of onclick alert function using Javascript:
CLICK HERE

This is what you must type:
<a href="javascript: alert('This is the alert')">CLICK HERE</a>

CREATING STATUS BAR USING JAVASCRIPT

If you see, when loading a website, you will find at the bottom of the window ,there will be "loading", and when the page is loladed, the status bar will contain "done".
If you want to change the status bar of your website, use this following code:
window.defaultStatus="the stat that you want";

MAKING 'BACK' FUNCTION USING JAVASCRIPT

Here is example of back button that use Javascript:

Go to previous page
Here is the code to  be written at HTML tab at Blogger:
<a href="javascript:history.go(-1)">Go to previous page</a>