@j2inn/app/dist/remote/ResourceElement.js

J2 Innovations core application framework

/*
 * Copyright (c) 2021, J2 Innovations. All Rights Reserved
 */
var __classPrivateFieldSet = (this && this.__classPrivateFieldSet) || function (receiver, state, value, kind, f) {
    if (kind === "m") throw new TypeError("Private method is not writable");
    if (kind === "a" && !f) throw new TypeError("Private accessor was defined without a setter");
    if (typeof state === "function" ? receiver !== state || !f : !state.has(receiver)) throw new TypeError("Cannot write private member to an object whose class did not declare it");
    return (kind === "a" ? f.call(receiver, value) : f ? f.value = value : state.set(receiver, value)), value;
};
var __classPrivateFieldGet = (this && this.__classPrivateFieldGet) || function (receiver, state, kind, f) {
    if (kind === "a" && !f) throw new TypeError("Private accessor was defined without a getter");
    if (typeof state === "function" ? receiver !== state || !f : !state.has(receiver)) throw new TypeError("Cannot read private member from an object whose class did not declare it");
    return kind === "m" ? f : kind === "a" ? f.call(receiver) : f ? f.value : state.get(receiver);
};
var _ResourceElement_resource, _ResourceElement_loadListeners, _ResourceElement_errorListeners;
/**
 * Handles loading a resource DOM element and listening for when it's
 * finished or failed to load.
 *
 * This is designed to handle race conditions whereby a resource
 * added but not yet fully loaded. Event handlers can be registered
 * even after a resource has loaded with event handlers being fired.
 */
export class ResourceElement {
    constructor(resource) {
        _ResourceElement_resource.set(this, void 0);
        this.ready = false;
        this.failed = false;
        _ResourceElement_loadListeners.set(this, new Set());
        _ResourceElement_errorListeners.set(this, new Set());
        /**
         * A callback made by the resource DOM element for
         * when the resource has loaded successfully.
         */
        this.onload = () => {
            this.ready = true;
            this.failed = false;
            this.checkLoaded();
        };
        /**
         * A callback made by the resource DOM element for
         * when the resource fails to load.
         */
        this.onerror = () => {
            this.ready = false;
            this.failed = true;
            this.checkLoaded();
        };
        __classPrivateFieldSet(this, _ResourceElement_resource, resource, "f");
        __classPrivateFieldGet(this, _ResourceElement_resource, "f").onload = this.onload;
        __classPrivateFieldGet(this, _ResourceElement_resource, "f").onerror = this.onerror;
    }
    /**
     * Add event listeners for when a resource has loaded or failed to load.
     *
     * @param onLoad A callback for when the resource has loaded successfully.
     * @param onError A callback for when the resource has failed to load.
     */
    addListeners(onLoad, onError) {
        __classPrivateFieldGet(this, _ResourceElement_loadListeners, "f").add(onLoad);
        __classPrivateFieldGet(this, _ResourceElement_errorListeners, "f").add(onError);
        this.checkLoaded();
    }
    /**
     * Removes load and error event listeners.
     *
     * @param onLoad A callback for when the resource has loaded successfully.
     * @param onError A callback for when the resource has failed to load.
     */
    removeListeners(onLoad, onError) {
        __classPrivateFieldGet(this, _ResourceElement_loadListeners, "f").delete(onLoad);
        __classPrivateFieldGet(this, _ResourceElement_errorListeners, "f").delete(onError);
    }
    /**
     * Checks whether any callback handlers need to be invoked.
     */
    checkLoaded() {
        if (this.ready || this.failed) {
            if (this.ready) {
                for (const onLoad of __classPrivateFieldGet(this, _ResourceElement_loadListeners, "f")) {
                    onLoad();
                }
            }
            else if (this.failed) {
                for (const onError of __classPrivateFieldGet(this, _ResourceElement_errorListeners, "f")) {
                    onError();
                }
            }
            // As all of the event handlers have fired remove them
            // as they don't need to fire again.
            __classPrivateFieldGet(this, _ResourceElement_loadListeners, "f").clear();
            __classPrivateFieldGet(this, _ResourceElement_errorListeners, "f").clear();
        }
    }
}
_ResourceElement_resource = new WeakMap(), _ResourceElement_loadListeners = new WeakMap(), _ResourceElement_errorListeners = new WeakMap();