☰

Library | querySelectorInterval

Use document.querySelector() to continuously look for an Element. Call a function when found. Powered by requestAnimationFrame.

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greatest.deepsurf.us/scripts/375023/1060699/Library%20%7C%20querySelectorInterval.js 

// ==UserScript==
// @name            Library: querySelectorInterval
// @namespace       org.sidneys.userscripts
// @homepage        https://gist.githubusercontent.com/sidneys/c6b91437cb89346281bb2f739c1d6ae2/raw/
// @version         0.7.4
// @description     Use document.querySelector() to continuously look for an Element. Call a function when found. Powered by requestAnimationFrame.
// @author          sidneys
// @icon            https://i.imgur.com/nmbtzlX.png
// @match           *://*/*
// ==/UserScript==


/**
 * ESLint
 * @exports
 */
/* exported querySelectorInterval, clearQuerySelectorInterval */


/**
 * Unique identifier returned by querySelectorInterval().
 * @typedef {Number} intervalHandle
 */

/**
 * This callback is displayed as a global member.
 * @callback intervalCallback
 * @param {Element} Element found by document.querySelector()
 */

/**
 * Repeatedly try to find (using a optional time delay) the first element
 * that is a descendant of a base element, and matches the selectors.
 * Call a callback with the found element as argument when successful.
 * Returns an identifier for removal via clearQuerySelectorInterval().
 * @param {Element} element - Base Element
 * @param {String} selectors - DOMString containing one or more selectors to match against
 * @param {intervalCallback=} callback - The callback that is called when an Element was found
 * @param {Number=} delay - Duration (ms) the timer should wait between executions
 * @return {intervalHandle} - Unique interval handle
 * @global
 */
let querySelectorInterval = (element, selectors, callback = () => {}, delay = 0) => {
    // console.debug('querySelectorInterval')

    // requestAnimationFrame identifier
    let requestId

    // Initial timestamp
    let lastTimestamp = new Date().getTime()

    // Lookup Logic
    let lookup = () => {
        // Get current timestamp
        const currentTimestamp = new Date().getTime()

        // Get elapsed time (between timestamps)
        const elapsedDuration = currentTimestamp - lastTimestamp

        // Elapsed time larger than delay?
        if (elapsedDuration >= delay) {
            // Test if selectors finds a descendant beneath element
            const foundElement = element.querySelector(selectors)

            // Element found
            if (foundElement) {
                callback(foundElement)
            }

            // Update last timestamp
            lastTimestamp = new Date().getTime()
        }

        // Rerun Lookup
        requestId = window.requestAnimationFrame(lookup)
    }

    // Initial lookup
    requestId = window.requestAnimationFrame(lookup)

    return requestId
}

/**
 * Cancels intervals scheduled via querySelectorInterval().
 * @param {intervalHandle} handle - Unique interval handle
 * @global
 */
let clearQuerySelectorInterval = (handle) => {
    // console.debug('clearQuerySelectorInterval')

    // Cancel interval
    window.cancelAnimationFrame(handle)
}