Files
Nicholas Carrigan (he/him) 3da4be21bb chore: seed chinese traditional (#42005)
Seeds the chinese traditional files manually so we can deploy to
staging.
2021-05-05 22:43:49 +05:30

101 lines
2.0 KiB
Markdown

---
id: 5cdafbe72913098997531682
title: 使用 catch 處理 Promise 失敗的情況
challengeType: 1
forumTopicId: 301204
dashedName: handle-a-rejected-promise-with-catch
---
# --description--
當 promise 失敗時會調用 `catch` 方法。 當 promise 的 `reject` 方法執行時會直接調用。 用法如下:
```js
myPromise.catch(error => {
});
```
`error` 是傳入 `reject` 方法的參數。
# --instructions--
給 promise 添加 `catch` 方法。 用 `error` 作爲回調函數的參數,並把 `error` 打印到控制檯。
# --hints--
應該在 promise 上調用 `catch` 方法。
```js
assert(
__helpers.removeWhiteSpace(code).match(/(makeServerRequest|\))\.catch\(/g)
);
```
`catch` 方法應該有一個回調函數,回調函數參數爲 `error`
```js
assert(errorIsParameter);
```
應該打印 `error` 到控制檯。
```js
assert(
errorIsParameter &&
__helpers
.removeWhiteSpace(code)
.match(/\.catch\(.*?error.*?console.log\(error\).*?\)/)
);
```
# --seed--
## --after-user-code--
```js
const errorIsParameter = /\.catch\((function\(error\){|error|\(error\)=>)/.test(__helpers.removeWhiteSpace(code));
```
## --seed-contents--
```js
const makeServerRequest = new Promise((resolve, reject) => {
// responseFromServer is set to false to represent an unsuccessful response from a server
let responseFromServer = false;
if(responseFromServer) {
resolve("We got the data");
} else {
reject("Data not received");
}
});
makeServerRequest.then(result => {
console.log(result);
});
```
# --solutions--
```js
const makeServerRequest = new Promise((resolve, reject) => {
// responseFromServer is set to false to represent an unsuccessful response from a server
let responseFromServer = false;
if(responseFromServer) {
resolve("We got the data");
} else {
reject("Data not received");
}
});
makeServerRequest.then(result => {
console.log(result);
});
makeServerRequest.catch(error => {
console.log(error);
});
```