Windows HTAs are very simple to create, but can be made into powerful and useful tools. This short tutorial shows how to quickly obtain stock quotes from Yahoo! Finance.
Every HTA (HTML Application) consists of three sections:
The head section
the script section
the body section
This short tutorial will show how just quickly these three sections can be combined to produce a useful desktop application - in this case a desktop application for obtaining stock quotes from Yahoo! Finance.
The Head Section
The head section of an HTA is used to set up it's general properties, and these are enclosed within the HTA:APPLICATION tag:
<head>
<HTA:APPLICATION
ID="yahoohta"
APPLICATIONNAME="Yahoo! Finance Stock Quotes"
SCROLL="yes"
SINGLEINSTANCE="yes"
>
</head>
In this examle:
the ID and name are set
a scrollbar is enabled
only a single instance of the application is allowed to be run at any time
The Script Section
The script section is, of course, where all of the functionality of the HTA resides. This particular application uses VBScript, but it could just as easily have been written using Javascript. The Application itself will:
define a list of company details for which stock quotes are to be retrieved
define a list of additional data fields which may also be retrieved
obtain the details from Yahoo! Finance (which will be dependant on user selections from the above)
Part of the process will be to format the Yahoo! Finance url, which must be in the form:
This is a task that can be achieved relatively easily with VBScript:
<script language="VBSCRIPT">
document.title = yahoohta.APPLICATIONNAME
field_array = array ( _
array ("c1","Change in Stock Quote"), _
array ("d1", "Date"))
company_array = array ( _
array ("MSFT","Microsoft"), _
array ("NOVL","Novell Inc."), _
array ("RHT", "Redhat Inc."))
Here, the company and field details are hard coded into arrays, but they can easily be read from files or a database; wherever these arrays come from they can be used in subroutines to format the information for use in the body section:
Next the url is sent to the server using the XML HTTP object:
Set xmlhttp = CreateObject("microsoft.xmlhttp")
xmlhttp.open "get", url, false
xmlhttp.send ""
Then the response from Yahoo! Finance must be processed:
'Remove unwanted speech marks:
ip_data = Replace(xmlhttp.responseText,"""","")
'Load each kine of the data into an array:
ip_data = split(ip_data, vbcrlf)
op_data = "<b>Stock Quotes</b><table>"
For Each line In ip_data
op_data = op_data & "<tr>"
'Split each line of data into an array of fields:
line_data = split(line, ",")
'Then display the fields in a table:
For Each member In line_data
op_data = op_data & "<td>" & member & "</td>"
next
op_data = op_data & "</tr>"
next
op_data = op_data & "</table>"
Finally the processed data can be displayed:
output_area.innerHTML = op_data
As mentioned before, VBScript only supports on error resume next and so any errors must be handled at the end of the subroutine:
If (Err.Number <> 0) Then
output_area.innerHTML = "Unable to obtain stock quotes"
End If
End Sub
</script>
The Body Section
The body section is used to define the GUI (Graphical User Interface) and uses HTML to do this, as well as some of the subroutines defined in the script section:
If the three sections are stored in a text file with a .hta extension (for example yahoo.hta) then the HTA can be run by double clicking on its icon in Windows Explorer; and this simple, but useful, application will be available for use on any Windows pc to which it is copied.
The copyright of the article A Windows HTA Tutorial in Computer Programming Tutorials is owned by Mark Alexander Bain. Permission to republish A Windows HTA Tutorial in print or online must be granted by the author in writing.
