example.js

function setPageUnchangedFlag(browser) {
    browser.execute(function () {
        window.__pageUnchanged = true
    })
}

function getPageUnchangedFlag(browser) {
    return browser.execute(function () {
        return window.__pageUnchanged
    }).value
}

exports.getPageReadyState = function () {
    return this.execute(function () {
        return document.readyState
    }).value
}

exports.waitForPageChange = function (timeout) {
    setPageUnchangedFlag(this)

    this.waitUntil(() => (
        !getPageUnchangedFlag(this)
        &&
        this.getPageReadyState() === 'complete'
    ), timeout)
}

exports.runAndWaitForPageChange = function (callback, timeout) {
    setPageUnchangedFlag(this)

    callback()
    
    this.waitUntil(() => (
        !getPageUnchangedFlag(this) 
        && 
        this.getPageReadyState() === 'complete'
    ), timeout)
}