waitFor.js

/**
 *
 * @param {() => boolean} pred
 * @param {{
 *  delay?: number,
 *  maxAttempts?: number
 * }} [options]
 * @returns {Promise<void>}
 */
export const waitFor = (pred, options) => new Promise((resolve, reject) => {
    options = {
        delay: 100,
        maxAttempts: -1,
        ...options
    };
    let attempts = options.maxAttempts;
    const loop = () => {
        if (attempts-- === 0){
            reject(new Error("Max attempts exceeded."));
        }
        if (pred()){
            resolve();
        }
        setTimeout(loop, options.delay);
    }
    loop();
});