Subject Re: LOGICAL ERROR From Mervyn Bick <invalid@invalid.invalid> Date Sun, 11 Mar 2018 20:18:24 +0200 Newsgroups dbase.getting-started On 2018-03-11 3:52 PM, Mustansir Ghor wrote: > Dear > > I seem to get confused many times use of 'this' object.  When following PBRCANCEL_onclick() is executed, there is change in value of form.eamount. Therefore function  Eamount-Onchange() will execute. On its execution what will 'this' refer to ? > > Best Regards > Mustansir > >   function PBRCANCEL_onClick() >    form.eamount.value=0 >     form.cbregname.setfocus() >   return > >   function EAMOUNT_onChange() >          if this.value>0 >          form.pbrcancel.enabled=true >          form.pbrsave.enabled=true >         else >          form.pbrcancel.enabled=false >          form.pbrsave.enabled=false >         endif >                  >    return > 'This' is form.eamont in this case.  The event handler is executed by form.eamont when the value changed.  As you use PBRCANCEL to save 0 to form.eamont the event handler will immediately disable PBRCANCEL and PBRSAVE. These pushbuttons are disabled until, say, the edit pushbutton is pressed which would execute code to enable them again. If you had executed the event handler from, say, the form's onOpen event handler 'this' would be the form.  The form doesn't have a value property so if it doesn't have a user-defined value property there would be an error. 'This' in a function is always the object which executes the function. If, for instance, instead of assigning different onChange event handlers to several entryfields you assign the same event handler to each entryfield you can use this.name to decide what to do depending on which entryfield changed.     function entryfield_onChange()       if this.name = 'ENTRYFIELD1'           do something       elseif this.name = 'ENTRYFIELD2'           do something else       elseif this.name = 'ENTRYFIELD3'           do something different       endif       return Mervyn.