switch-layer-on-off.jsx

// shut on/off of layer visibility
// written for
// http://stackoverflow.com/questions/19882937/after-effects-extendscript-hide-and-show-video-layers-randomly
// ae scripting guide
// http://blogs.adobe.com/aftereffects/files/2012/06/After-Effects-CS6-Scripting-Guide.pdf

    fun();
    function fun(){
    app.beginUndoGroup("XXX");// undo possiblilty
    // prerequisites
    // if there is no comp active return
    var curComp = app.project.activeItem;
      if (!curComp || !(curComp instanceof CompItem)){
        alert("noComp");
        return;
      };

    // loop all layers of comp 1 based Array
    for(var i = 1; i < curComp.layers.length +1;i++){
      // check name
      if(curComp.layers[i].name =="foo"){
        // turn into opposite
        curComp.layers[i].enabled =  !curComp.layers[i].enabled;
        }
      }
    app.endUndoGroup();
    }