console.log("text") 当在 javascript 中没有使用 selenium 的可用按钮元素时

Question

我想 console.log("No element") 当没有可用的按钮元素但它不起作用时。

const {Builder, By} = require("selenium-webdriver");

let driver = new Builder().forBrowser("chrome").build();

async function myfun(){

    await driver.get("website")
    await driver.findElement(By.linkText("yes")).click();
    await driver.findElement(By.linkText("yes")).click();
    await driver.sleep(500);
    await driver.findElement(By.id("inputfield")).sendKeys("name");

    setInterval(function(err){
        if (err){
            console.log("No element");
        }else{
            driver.findElement(By.tagName("button")).click();
        }
    }, 1000);

}
myfun()

我收到这些错误：

(node:16248) UnhandledPromiseRejectionWarning: NoSuchElementError: no such element: Unable to locate element: {"method":"css selector","selector":"button"}
  (Session info: chrome=81.0.4044.92)

(node:16248) 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(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:16248) [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.

我也尝试过 try/cath 方法，但没有成功。

try {
    driver.findElement(By.tagName("button")).click();
} catch(err) {
    console.log("No element")
}

Answer 1

归功于用户 Arthur Weborg. I found this post which solved my problem perfectly. It is copied from another thread. For a clearer understanding see the full thread here。

选择的答案没有按预期工作（err.state 是 undefined 并且总是抛出 NoSuchElementError）——尽管使用可选回调的概念仍然有效。

由于我遇到了与 OP 引用相同的错误，我认为在确定目标元素是否存在时应该引用 NoSuchElementError。顾名思义，当元素不存在时抛出的错误。所以errorCallback中的条件应该是：

err instanceof webdriver.error.NoSuchElementError

所以完整的代码块如下（对于那些利用该语法的人，我也使用 async/await）：

var existed = await driver.findElement(webdriver.By.id('test')).then(function() {
    return true;//it existed
}, function(err) {
    if (err instanceof webdriver.error.NoSuchElementError) {
        return false;//it was not found
    } else {
        webdriver.promise.rejected(err);
    }
});
//handle value of existed appropriately here

console.log("text") 当在 javascript 中没有使用 selenium 的可用按钮元素时

console.log("text") when there is no button element avalible using selenium in javascript

javascript

debugging

selenium

setinterval

node.js