• Adobe After Effects Expressions

  Detect if layer was deleted via scripting

  Posted by Malte Hillebrand on January 4, 2020 at 2:02 pm

  Is there any way to detect if a layer was deleted by the user and then execute some code?

  If I delete a layer stored as a variable and then call the variable it tells me that the object is invalid. Comparing it to a null doesn’t return true or false as it’s not really an object (?).
  Not sure which way to go to react to a user deleting a certain layer, created by and crucial to my script.

  Andrei Popa replied 6 years, 8 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Andrei Popa

  January 4, 2020 at 3:26 pm

  You could use a try/catch block. Something like this

  
try {
var a = app.project.item(1).layer("Shape Layer 1").name;
alert(a);
}catch(e){
alert("You shouldn't delete the layer");
}


  Another way would be to compare the layer to a null. You must do this before trying to access any of the property. If you do (app.project.item(1).layer(“Shape Layer 1”) == null) you get a true value if the layer does not exist. However, if you try to access any property of a layer that does not exist, you get an error. Something like this doesn’t work (app.project.item(1).layer(“Shape Layer 1”) == null)

  Andrei
  My Envato portfolio.

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