带打字稿的量角器：失败：无法读取未定义的属性“presenceOf”

Question

我正在尝试使用量角器、打字稿等待元素存在。

这是我的代码：

import { browser, by, element } from 'protractor';
import { protractor } from 'protractor/built/ptor';

export class LoginPage {

    title = element(by.css('my-page > h3'));

    async openMyPage() {
        await browser.get(browser.baseUrl);
        await browser.wait(protractor.ExpectedConditions.presenceOf(this.title), 5000,
            "Title does not appear during 5 seconds")
    }
}

失败并出现错误：Failed: Cannot read property 'presenceOf' of undefined。

有人可以帮我理解这个原因吗？以及如何解决？ 谢谢

Answer 1

试试这样：

import { browser, by, element, ElementFinder, protractor } from 'protractor';

export class NameofClass {

public title: ElementFinder;

constructor() {

this.title = element(by.css('my-page > h3'));
}

async openMyPage() {
        await browser.get(browser.baseUrl);
        await browser.wait(protractor.ExpectedConditions.presenceOf(this.title), 5000,
            "Title does not appear during 5 seconds")
    }
}