93 lines
2.1 KiB
Markdown
93 lines
2.1 KiB
Markdown
---
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id: 5cdafbd72913098997531681
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title: 用 then 處理 Promise 完成的情況
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challengeType: 1
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forumTopicId: 301203
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dashedName: handle-a-fulfilled-promise-with-then
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---
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# --description--
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當程序需要花費未知的時間才能完成時（比如一些異步操作），一般是服務器請求，promise 很有用。 服務器請求會花費一些時間，當結束時，需要根據服務器的響應執行一些操作。 這可以用 `then` 方法來實現， 當 promise 完成 `resolve` 時會觸發 `then` 方法。 例子如下：
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```js
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myPromise.then(result => {
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});
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```
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`result` 即傳入 `resolve` 方法的參數。
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# --instructions--
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給 promise 添加 `then` 方法。 用 `result` 做爲回調函數的參數並將 `result` 打印在控制檯。
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# --hints--
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應該給 promise 方法調用 `then` 方法。
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```js
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assert(
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__helpers.removeWhiteSpace(code).match(/(makeServerRequest|\))\.then\(/g)
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);
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```
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`then` 方法應該有一個回調函數，回調函數參數爲 `result`。
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```js
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assert(resultIsParameter);
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```
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應該打印 `result` 到控制檯。
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```js
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assert(
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resultIsParameter &&
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__helpers
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.removeWhiteSpace(code)
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.match(/\.then\(.*?result.*?console.log\(result\).*?\)/)
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);
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```
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# --seed--
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## --after-user-code--
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```js
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const resultIsParameter = /\.then\((function\(result\){|result|\(result\)=>)/.test(__helpers.removeWhiteSpace(code));
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```
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## --seed-contents--
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```js
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const makeServerRequest = new Promise((resolve, reject) => {
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// responseFromServer is set to true to represent a successful response from a server
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let responseFromServer = true;
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if(responseFromServer) {
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resolve("We got the data");
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} else {
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reject("Data not received");
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}
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});
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```
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# --solutions--
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```js
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const makeServerRequest = new Promise((resolve, reject) => {
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// responseFromServer is set to true to represent a successful response from a server
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let responseFromServer = true;
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if(responseFromServer) {
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resolve("We got the data");
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} else {
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reject("Data not received");
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}
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});
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makeServerRequest.then(result => {
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console.log(result);
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});
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```
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