112 lines
2.0 KiB
Markdown
112 lines
2.0 KiB
Markdown
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---
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id: 587d7b7d367417b2b2512b1e
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title: 使用 Object.keys() 生成由對象的所有屬性組成的數組
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challengeType: 1
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forumTopicId: 301160
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dashedName: generate-an-array-of-all-object-keys-with-object-keys
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---
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# --description--
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我們可以給 `Object.keys()` 方法傳入一個對象作爲參數,來生成包含對象所有鍵的數組。 這會返回一個由對象中所有屬性(字符串)組成的數組。 需要注意的是,數組中元素的順序是不確定的。
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# --instructions--
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請完成 `getArrayOfUsers` 函數的實現,使其返回一個由輸入對象中的所有屬性所組成的數組。
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# --hints--
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`users` 對象應該只包含 `Alan`、`Jeff`、`Sarah`、`Ryan` 這 4 個屬性。
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```js
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assert(
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'Alan' in users &&
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'Jeff' in users &&
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'Sarah' in users &&
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'Ryan' in users &&
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Object.keys(users).length === 4
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);
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```
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`getArrayOfUsers` 函數應返回一個包含 `users` 對象中所有屬性的數組。
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```js
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assert(
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(function () {
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users.Sam = {};
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users.Lewis = {};
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let R = getArrayOfUsers(users);
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return (
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R.indexOf('Alan') !== -1 &&
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R.indexOf('Jeff') !== -1 &&
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R.indexOf('Sarah') !== -1 &&
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R.indexOf('Ryan') !== -1 &&
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R.indexOf('Sam') !== -1 &&
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R.indexOf('Lewis') !== -1
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);
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})() === true
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);
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```
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# --seed--
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## --seed-contents--
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```js
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let users = {
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Alan: {
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age: 27,
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online: false
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},
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Jeff: {
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age: 32,
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online: true
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},
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Sarah: {
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age: 48,
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online: false
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},
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Ryan: {
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age: 19,
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online: true
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}
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};
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function getArrayOfUsers(obj) {
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// Only change code below this line
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// Only change code above this line
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}
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console.log(getArrayOfUsers(users));
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```
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# --solutions--
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```js
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let users = {
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Alan: {
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age: 27,
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online: false
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},
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Jeff: {
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age: 32,
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online: true
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},
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Sarah: {
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age: 48,
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online: false
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},
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Ryan: {
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age: 19,
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online: true
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}
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};
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function getArrayOfUsers(obj) {
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return Object.keys(obj);
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}
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console.log(getArrayOfUsers(users));
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```
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