Javascript: what's your browser?


I Know what browser you are using now...look here:

Browser Name:
Browser Version:
Browser Code Name:
User-Agent:
And this is the HTML page:

<html>
<head>
<script language="JavaScript">
<!--

function whatBrowser() {
document.Form1.Name.value=navigator.appName;
document.Form1.
Version.value=navigator.appVersion;
document.Form1.
Code.value=navigator.appCodeName;
document.Form1.
Agent.value=navigator.userAgent;
}// -->
</script>
</head>
<BODY
onLoad="whatBrowser()">
<CENTER>
<TABLE BORDER>
<FORM NAME="
Form1">
<TR>
<TD> Browser Name: </TD>
<TD> <INPUT TYPE="text" NAME="
Name" Size="35"></TD>
</TR>
<TR>
<TD> Browser Version: </TD>
<TD> <INPUT TYPE="text" NAME="
Version" Size="35"></TD>
</TR>
<TR>
<TD> Browser Code Name: </TD>
<TD> <INPUT TYPE="text" NAME="
Code" Size="35"></TD>
</TR>
<TR>
<TD> User-Agent: </TD>
<TD> <INPUT TYPE="text" NAME="
Agent" Size="35"></TD>
</TR>
</FORM>
</TABLE>
</CENTER>
</body>
</html>

Ok, ok, I'm going to explain...

As you can see, although this HTML source is quite long, there are a few of thing to understand. I wrote them in different colors.

Blue colors

These things are objects: Document and Navigator

Orange colors

These things are properties

Ok, the Navigator object has some properties, for example its name (appName) and its version (appVersion). You can read these properties so: Navigator.property...

In the table above, there are 4 fields. Each field has a name. For example, the second field's name is 'Version'. Notice that Javascript is case sensitive, so 'Version' is quite different from 'version'; if you forget that, you will get an error by Javascript.

Do you remember the objects hierarchy? Well, to use the field 'Version' you have to call it so: Document.Form_name.Version. There is just a document object, so you have not to call it in a specific way. But a single document could contain several 'form', and so you have to specify the name of the form which you want to use. A form could contain several fields, buttons and so on, so you have to specify the name of the field which you want to use (for example 'Version'). Value is a property. A field has several properties: value is one of them. If you want to put something inside of a field, you have to put it inside of 'value'. In other words you have to assign a value to the field.

Hence this statement: Document.Form1.Version.Value=Navigator.appVersion

In this way, you are saying to the browser: 'hey, browser, please assign your version to the value of field Version of the form Form1 of the Document...'.

Finally OnLoad: this is an event-handler. The event is Load. So, when the HTML page is loading, a Load event occurs. In this case, the OnLoad event-handler calls the whatBrowser function.

As you can see, the real Javascript code is just a few of lines!


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