By now you should be familiar with the two most important event handler approaches in Internet Explorer 4.0x (HTML attributes and JavaScript properties). These approaches are important because they are also supported by Navigator 3.0x and above. That is, they are cross-browser approaches. However, Internet Explorer 4.0x also supports explicit event handler scripts.

An explicit event handler script is an ordinary script that executes only when a specific event occurs for a given object. Take a look at the following script:

<SCRIPT LANGUAGE="JavaScript" EVENT="onclick" FOR="document">
<!--

alert("Thank you for clicking the mouse button.");

// -->
</SCRIPT>

If you're running any version of Netscape Navigator, or version 3.0x of Microsoft Internet Explorer, the alert dialog box pops up immediately when you load the page. Nonetheless, if you're using Internet Explorer 4.0x, the script is executed only when a click event (EVENT="onclick") occurs for the document object (FOR="document"). Notice that the EVENT attribute gets an event handler, not an event.

When dealing with a button's event handler, the script must be placed within the form, unless the button has a unique identifier:

<FORM>
<INPUT TYPE="button" NAME="myButton" VALUE="click here">
<SCRIPT LANGUAGE="JavaScript" EVENT="onclick" FOR="myButton">
<!--

alert("Thank you for clicking the button.");

// -->
</SCRIPT>
</FORM>

For more information on event handler scoping for scripts, refer to Microsoft's documentation.

Explicit event handler scripts are pretty useless, because they aren't supported by most browsers. Browsers that do not recognize the EVENT and FOR attributes of the <SCRIPT> tag simply ignore them, so the script executes immediately when the page loads.