willsummers

var expr = 'value + [0, Math.sin(time * 2) * 50]'; // example expression

app.beginUndoGroup("Apply Expression");

var comp = app.project.activeItem;
if (comp && comp instanceof CompItem) {
    for (var i = 0; i < comp.selectedLayers.length; i++) {
        var layer = comp.selectedLayers[i];
        layer.property("Transform").property("Position").expression = expr;
    }

willsummers

//Find Top most Layer Index
topStackIndex = function(){
  for (i = 1; i <= thisComp.numLayers; i++){ 
      if (i == index) continue; 
      my_layer = thisComp.layer(i); 
      if (! (my_layer.hasVideo && my_layer.active)) continue; 
      if (time >= my_layer.inPoint && time < my_layer.outPoint){ 
          try{ 
              return my_layer.index; 
          }catch(err1){ 

willsummers

//KeyAllanimProps.jsx
// October 2013 Will Summers 
//willsummers.wordpress.com


var proj = app.project
app.beginUndoGroup("Keyframe all Animation Properties")

if (proj) {

willsummers

//Apply this expression to the Source Text property of a text layer at the top of a stack.
//The for loop in here iterates down from the top to find the first layer that is active and gets its duration.

nextActiveLayer = thisLayer;
for (i = thisLayer.index + 1; i <= thisComp.numLayers; i++) {
	if (thisComp.layer(i).active) {
		nextActiveLayer = thisComp.layer(i);
		break;
	}
}