Need a script to write an expression to multiple layers.

I am trying to write a script (my first) that will write a wiggle expression to all the layers that I select. I am well versed in expression but not scripts. So far I have tried many configurations and most came back with errors. Here is my current script:

app.project.activeItem.layer(1).property("position").expression = "wiggle(0.5,25)";

It does not give me an error message, but it also does not apply the expression. I have 106 layers that I want to independently, slowly wiggle. Any help is appreciated.