Helper functions to work with triggers in Lens Studio

TriggerHelpers.js

// -----JS CODE-----
//NOTE:
//To this scipt to work you need to:
// - Put 'Behavior' script on the very top of Objects hierarchy. Use 
//   + > Helper Scripts > Behavior to add it. You can leave that script
//   to work 'On Awake'

// - Put this script on top of the Objects hierarchy, AFTER behavior. Bind
//   this script to 'On Start', NOT 'On Awake'

/**
 * Sends the trigger with specified name
 * 
 * @param {string} triggerName
 */
global.send = function(triggerName) {
    global.behaviorSystem.sendCustomTrigger(triggerName);
};

/**
 * Subscribes a `handler` function to the trigger with name
 * `triggerName`. `handler` will be called every time somebody
 * sends the trigger with name `triggerName`
 * 
 * @param {string} triggerName
 * @param {() => void} handler
 */
global.subscribe = function(triggerName, handler) {
    global.behaviorSystem.addCustomTriggerResponse(triggerName, handler);
};

/**
 * Unsubscribes `handler` from the trigger with name `triggerName`. 
 * Note that `handler` must be *exactly same* function object as the one
 * that was passed to `global.subscribe()`
 * 
 * @param {string} triggerName
 * @param {() => void} handler
 */
global.unsubscribe = function(triggerName, handler) {
    global.behaviorSystem.removeCustomTriggerResponse(triggerName, handler);
};

/**
 * Subscribes to the trigger with `triggerName`, and unsubscribes 
 * from it once it has happened. That is, `handler` function will be called
 * only once - on the first occurence of the trigger
 * 
 * @param {string} triggerName
 * @param {() => void} handler
 */
global.subscribeOnce = function(triggerName, handler) {
    var callback;

    callback = function() {
        handler();
        global.unsubscribe(triggerName, callback);
    };

    global.subscribe(triggerName, callback);
};

/**
 * Subscribes to the all triggers from the `triggers` array. Once any of 
 * the triggers has happened, runs that `handler` function and 
 * unsubscribes from fursther occurences of all the triggers.
 * 
 * That is, `handler` will be called only once - once any of the triggers
 * from the `triggers` array has happened. It can be any trigger - whichever
 * happened first.
 *
 * Handler can optionally take one parameter - the name of the trigger that 
 * caused `handler` to run
 *
 * @param {string[]} triggers
 * @param {(triggerName?: string) => void} handler
 */
global.subscribeOnceAny = function(triggers, handler) {
    var unsubscribers = [];

    var unsubscribeFromAll = function() {
        unsubscribers.forEach(function(u) {
            u();
        });
    };

    triggers.forEach(function(triggerName) {
        var callback = function() {
            handler(triggerName);
            unsubscribeFromAll();
        };

        global.subscribe(triggerName, callback);

        unsubscribers.push(function() {
            global.unsubscribe(triggerName, callback);
        });
    });
};