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Groups > comp.lang.javascript > #32134

Re: Empty function

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On 08.01.2017 06:49, Andrew Poulos wrote:

> var Drag = {
>   obj : null,
>   init: function(o) {
>     o.onmousedown = Drag.start;
>     o.root.onDrag = function() {}; //--> what does this line do?
>   },
>   start: function(e) {
>     document.onmousemove = Drag.drag;
>     document.onmouseup = Drag.end;
>     return false;
>   },
>   drag: function(e) {
>     Drag.obj.root.onDrag(nx, ny);
>     return false;
>   },
>   end: function() {
>     document.onmousemove = null;
>     document.onmouseup   = null;
>   }
> };
>
> What I don't follow is what the line
>     o.root.onDrag = function() {};
> is doing. If I comment the line out the code "doesn't work". What's the
> purpose of setting an event to an empty function?


Is that the complete code? I don't see any nx or ny variables declared 
anywhere that are used in
   Drag.obj.root.onDrag(nx, ny)
so I guess somewhere else the onDrag function is assigned or can be 
assigned a handler that does have a body doing something.

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Thread

Empty function Andrew Poulos <ap_prog@hotmail.com> - 2017-01-08 16:49 +1100
  Re: Empty function Martin Honnen <martin.honnen@gmx.de> - 2017-01-08 08:29 +0100
    Re: Empty function Andrew Poulos <ap_prog@hotmail.com> - 2017-01-08 20:05 +1100
      Re: Empty function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-01-08 23:40 +0100
        Re: Empty function Andrew Poulos <ap_prog@hotmail.com> - 2017-01-09 10:47 +1100
          Re: Empty function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-01-09 01:10 +0100
  Re: Empty function JJ <jj4public@vfemail.net> - 2017-01-08 20:53 +0700
  Re: Empty function "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2017-01-08 10:02 -0800
  Re: Empty function Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2017-01-08 23:21 +0100

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