javascript - 如何处理 "promise rejections are deprecated"

Question

我正试图让我的头脑围绕着 promise ，但我收到此错误，提示未处理的 promise 拒绝，但如果它被拒绝，我确实有一个catch!

任何人都可以帮我解决我做错的事情吗？

这是我的代码:

var webdriver = require('selenium-webdriver');

function searchTextOnGoogle() {
  var driver = new webdriver.Builder().forBrowser("chrome").build();

  driver.get("www.google.com").then(function() {
    driver.findElement(webdriver.By.linkText("Automation")).click().then(function() {
      driver.getTitle().then(function(title) {
        setTimeout(() => {
          console.log(title);
          driver.quit();
        }, 5000);
      });
    }).catch(function(err) {
      console.log(err);
    });
  });
}

错误:

(node:200092) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1) (node:200092) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

整个错误消息:

DevTools listening on ws://127.0.0.1:62260/devtools/browser/6dd5b3dc-f6bb-4147-9421-a6e0e172017b(node:191496) UnhandledPromiseRejectionWarning: InvalidArgumentError: invalid argument (Session info: chrome=79.0.3945.117) at Object.throwDecodedError (C:\promise\node_modules\selenium-webdriver\lib\error.js:550:15) at parseHttpResponse (C:\promise\node_modules\selenium-webdriver\lib\http.js:563:13) at Executor.execute (C:\promise\node_modules\selenium-webdriver\lib\http.js:489:26) at processTicksAndRejections (internal/process/task_queues.js:93:5) at async thenableWebDriverProxy.execute (C:\promise\node_modules\selenium-webdriver\lib\webdriver.js:699:17) (node:191496) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1) (node:191496) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Answer 1

无论抛出什么，如果您有 searchTextOnGoogle 返回一个与内部所有异步操作正确链接的 Promise，然后在调用 时调用 .catch searchTextOnGoogle，所有错误都应该被正确捕获。使用异步函数也可以使内容更具可读性:

const delay = ms => new Promise(res => setTimeout(res, ms));
async function searchTextOnGoogle() {
  var driver = new webdriver.Builder().forBrowser("chrome").build();

  await driver.get("www.google.com");
  await driver.findElement(webdriver.By.linkText("Automation")).click();
  const title = await driver.getTitle();
  await delay(5000);
  console.log(title);
  await driver.quit();
}

searchTextOnGoogle()
  .catch(console.log);

请注意，.quit 也返回一个 Promise，并且您需要将 setTimeout 内的异步操作与外部 Promise 链正确链接。

该错误可能是由以下行引起的:

driver.get("www.google.com");

docs say .get 的参数应该是完全限定的 URL，因此解决方案可能是将其更改为:

driver.get("https://www.google.com");

或者类似的东西。