Add Expression to Selected Properties.jsx

/**
 * @name Add Expression to Selected Properties
 * @version 1.0
 * @author Kyle Martinez <www.kyle-martinez.com>
 *
 * @description Add an expression to all selected properties.
 *
 * @license This script is provided "as is," without warranty of any kind, expressed or implied. In
 * no event shall the author be held liable for any damages arising in any way from the use of this
 * script.
 *
 * In other words, I'm just trying to help make life as an animator easier
 * "A rising tide lifts all boats." - John F. Kennedy, 1963
 */

(function() {
    app.beginUndoGroup("Add Expression to Selected Properties")
    var comp = app.project.activeItem;
    var properties = comp.selectedProperties;
    var numProperties = properties.length;
    for (var i = 0; i < numProperties; i++) {
        var property = properties[i];
        if (property.canSetExpression == true) {
            property.expression = 'posterizeTime(12); loopIn("cycle") + loopOut("cycle") - value;'
        }
    }
    app.endUndoGroup();
})()