Injecting JavaScript

Last Updated: 9/16/2008

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Topics in this section:
Overview
Areas of Implementation
Using Script Events
Writing JavaScript Events
More Script Events
Javascript Functions
Injecting JavaScript
Hidden Fields
Down Loading a File
JavaScript Solutions

Besides using the ScriptEvents property of IntraWeb Controls, there are multiple other possibilities to add JavaScript to your pages.

IWForm.JavaScript Property

This is the most native method to add JavaScript functions to your pages. Always add JavaScript enclosed with a <script> tag:

<script language="Javascript1.2">
function CheckLength(ASender)
{
 if (ASender.value.length < 6)
 {
   alert("Type more characters.");
 }   
}
</script>

Using the above code you can use CheckLength() in other ScriptEvents.

IWForm.ExtraHeader Property

The IWForm.ExtraHeader property can be used to specify extra content to be inserted in the <HEAD> section of the resulting HTML document.

AddToInitProc

IW Forms and controls have AddToInitProc property which adds JavaScript code to be executed immediately after the browser loads the HTML. You can easly access your application variables in JavaScript if include them into AddToInitProc.For example:

procedure TIWForm1.IWAppFormCreate(Sender: TObject); 
resourcestring 
  VerNum = '101010'; 
begin 
  AddToInitProc('window.alert("Load version '+ 
                VerNum+ 
                '")') 
end;

This code will result in alert window appear when browser loads your application.

AddValidation

AddValidation is an convenient way to add certain validation checks to your page before it gets submitted back to the server. For example to prevent users from submitting a form with blank IWEdits you could write IWForm.IWAppFormRender event handler as below:

procedure TIWForm1.IWAppFormRender(Sender: TObject); 
var 
  j : integer; 
begin 
  for j:=0 to ComponentCount-1 do 
  if Components[j] is TIWEdit then 
  with TIWEdit(Components[j]) do 
   begin 
     AddValidation(HTMLName+'IWCL.value.length==0', 
                  'You cannot leave '+FriendlyName+' empty') 
   end; 
end;

If the validation condition is true (IWCL.value.length==0), then the page will not submit and the validation message will be shown instead.