---
tags: Vue 直播班 - 2022 冬季班
---
# 🏅 Day 14 - 箭頭函式
參考文章: https://wcc723.github.io/javascript/2017/12/21/javascript-es6-arrow-function/
### 教學
箭頭函式的運用技巧如下：
```js=
// 傳統函式
function saySomething(string) {
return '接招' + string;
}
// 轉成箭頭函式
const saySomething = (string) => {
return '接招 ' + string;
}
```
```js=
// 當只有單行表達式時，可同時省略 return 及 {}
// 省略後依然保有回傳的特質
const saySomething = (string) => '接招 ' + string;
console.log(saySomething('菜鳥!'));
// 不過要注意，如果有使用 {}，就需要自行加上 return
const saySomething = (string) => {'接招 ' + string};
console.log(saySomething('菜鳥!')); // 會回傳 undefined
```
```js=
// 只有一個參數可以不加括號 ()
const saySomething = string => '接招 ' + string;
console.log(saySomething('菜鳥!'));
// 沒有參數、參數有兩個以上都不能省略 ()
const saySomething = () => '接招 菜鳥!';
console.log(saySomething());
```
題目
---
請將以下程式碼簡化為箭頭函式 (不影響結果的情況下進行最大簡化)
```js=
// 題目一
function sum(a, b) {
let c = a + b;
return c;
}
console.log(sum(5, 6));
// 題目二
function square(num) {
return num * num;
}
console.log(square(5))
// 題目三
setTimeout(function() {
console.log('延遲 1 秒');
}, 1000);
// 題目四
let arr = [1, 2, 3];
let arrNew = arr.map(function(item, i) {
return item * i;
});
console.log(arrNew);
// 題目五
let obj = {
fn: function fn2(a) {
return a * a;
}
}
console.log(obj.fn(10));
```
## 回報流程
將答案寫在 CodePen 並複製 CodePen 連結貼至底下回報就算完成了喔!
解答位置請參考下圖（需打開程式碼的部分觀看）
<!-- 解答：
// 題目一
const sum = (a, b) => {
let c = a + b;
return c;
}
console.log(sum(5, 6));
// 題目二
let square = num => num * num;
console.log(square(5));
// 題目三
setTimeout(() => console.log('延遲 1 秒'), 1000);
// 題目四
let arr = [1, 2, 3];
let arrNew = arr.map((item, i) => item * i);
console.log(arrNew);
// 題目五
let obj = {
fn: a => a * a
}
console.log(obj.fn(10));
-->
回報區
---
| Discord | CodePen / 答案 |
|:---------------:|:----------------------------------------------------------------------------:|
| Kimi#9564 | [CodePen](https://codepen.io/kimihu91/pen/xxJwjGm) |
| Wendy3#5615 | [Codepen](https://codepen.io/wendy03/pen/NWBxQbr) |
| bakiii | [codepen](https://codepen.io/aki168/pen/yLqygXp) |
| WeiJ#7376 | [CodePen](https://codepen.io/weij0/pen/zYLrgNj) |
| 冬天#5215 | [codepen](https://codepen.io/winter_/pen/eYjJqgy) |
| 阿榮#8277 | [CodePen](https://codepen.io/mogzbvfl-the-reactor/pen/jOpWgVy) |
| LinaChen#1796 | [CodePen](https://codepen.io/LinaChen/pen/yLqemgo) |
| popeye#5081 | [codepen](https://codepen.io/popeye_ux/pen/mdjVNRb) |
| YC#2522 | [CodePen](https://codepen.io/YCLu/pen/oNMjqYy) |
| 威0#6919 | [codepen](https://codepen.io/n0918679182/pen/eYjJqEV?editors=0012) |
| PeihanWang#2530 | [CodePen](https://codepen.io/PeihanWang/pen/vYaLogq?editors=0012) |
| ㄚ翔#8126 | [codepen](https://codepen.io/engineerjohnson/pen/abjdeya?editors=1111) |
| yuyu#6310 | [codepen](https://codepen.io/yuyu0905/pen/VwBeoWO?editors=0012) |
| AuroraC#6539 | [codepen](https://codepen.io/AuroraC/pen/ExpPqmp?editors=0012) |
| ChloeLo#4858 | [codepen](https://codepen.io/chloelo/pen/MWBKNmE) |
| suihsilan#9485 | [codepen](https://codepen.io/suihsilan/pen/jOpWgGm?editors=0010) |
| PH#2731 | [codepen](https://codepen.io/lokf9527/pen/yLqemoz?editors=0010) |
| kenki100#0068 | [Codepen](https://codepen.io/ken100/pen/RwBrXZb) |
| RJRS#9430 | [CodePen](https://codepen.io/RJRS/pen/xxJZvjm) |
| albee#9121 | [Codepen](https://codepen.io/albee-chang/pen/OJwMKEX?editors=1112) |
| Alex#9978 | [Codepen](https://codepen.io/datsxzqg-the-selector/pen/yLqempP?editors=0011) |
| JY#5712 | [CodePen](https://codepen.io/judy_123/pen/VwBeozO) |
| 泊岸#3466 | [CodePen](https://codepen.io/qoq77416416/pen/LYBGwmv?editors=0012) |
| JackC#0411 | [CodePen](https://codepen.io/key0329/pen/WNKrVWZ) |
| christina#6185 | [Codepen](https://codepen.io/chrisc0210/pen/NWBxQVv) |
| Chi#7605 | [Codepen](https://codepen.io/YoChi84/pen/poZgMYL) |
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| mandylai#4055 | [Codepen](https://codepen.io/mandy-lai-2/pen/vYaLooL) |
| Hilda#7085 | [Codepen](https://codepen.io/vwquikad-the-vuer/pen/RwBrXvW) |
| 威爾#1694 | [CodePen](https://codepen.io/WILL_Wu/pen/NWBNKGX) |
|yaru#6308|[CodePen](https://codepen.io/lszaietc/pen/YzjqKPw?editors=0011)|
|Eileen#6454|[CodePen](https://codepen.io/Eileen-io/pen/zYLqOGX)|
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|Fang#4680|[Codepen](https://codepen.io/std95174/pen/KKBzPxJ)
|jimmyFang#9575|[Codepen](https://codepen.io/pohxiqqo/pen/zYLqOeG?editors=0011)|
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|RainLiao#2616|[Codepen](https://codepen.io/billpop741/pen/NWBNKvM)|
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|大衛#4869|[Codepen](https://codepen.io/exnsrpjc/pen/XWBdrmG)|
|柚子#3958|[Codepen](https://codepen.io/as6625998/pen/ExpKxNN?editors=1011)|
|Ruby Chen#7452|[Codepen](https://codepen.io/ruby92429/pen/BaPKaQv?editors=0012)|
|黑白兔#0684|[Codepen](https://codepen.io/johnny329/pen/BaPKBvV)|
|Rena#6249|[Codepen](https://codepen.io/aureate0116/pen/jOpqOjq)|
|RyanC#6960|[Codepen](https://codepen.io/RyanYD/pen/wvxGBvB?editors=0011)|
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|Sean#3825|[CodePen](https://codepen.io/sean_1215/pen/gOjrYye?editors=0011)|
|出事了阿伯#9923|[CodePen](https://codepen.io/BradpittLai/pen/MWByagg?editors=1010)|
|Amberhh#2465|[codepen](https://codepen.io/Amberhh/pen/RwBrXBP) |
|hungya#0773|[codepen](https://codepen.io/hungya777/pen/PoBNPvr?editors=0011) |
|心幻羽#0056|[codepen](https://codepen.io/linglingsyu/pen/qByZbEy?editors=1111) |
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|ABOOS#6276|[Codepen](https://codepen.io/guhungyin/pen/ZEjWQVR?editors=0012)|
|Asher Xu#9297|[Codepen](https://codepen.io/kirakira72/pen/wvxGMRg)|
|Paul#7426|[CodePen](https://codepen.io/paul-1997/pen/jOpqqBK?editors=0011)|
|yoyo123456#0577|[CodePen](https://codepen.io/hungyoyo/pen/dyjMMJX?editors=0011)|
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|hannahTW#2224|[CodePen](https://codepen.io/hangineer/pen/poZgMaW?editors=0011)|
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|xin#1214|[CodePen](https://codepen.io/SiaoYao/pen/zYLqKdj)|
|Yishan#4902|[CodePen](https://codepen.io/gdjrehhw-the-animator/pen/WNKwvYa?editors=0011)|
|Mia小福#4473|[CodePen](https://codepen.io/a0950271/pen/vYaGXrB)|
|enolachen#8031|[CodePen](https://codepen.io/Chen-Enola/pen/poZyExd)|
|Austyn#0949|[CodePen](https://codepen.io/fish90547/pen/vYaGyzm?editors=0012)|
|jacky010080#0880|[CodePen](https://codepen.io/Yen-Jung-Chen/pen/yLqOVqw?editors=1011)|
Zack_P#1805|[CodePen](https://codepen.io/tmzazirh-the-animator/pen/WNKwoLa?editors=1011)|
ViNci#4273|[CodePen](https://codepen.io/ViNciSyo/pen/oNMxeQR)|
| 薯餅#3581 | [CodePen](https://codepen.io/ColdingPoTaTo/pen/OJwNjBX) | | | |
| --------------------- | --------------------------------------------------------------------------- | --- | --------------- | --------------------------------------------------------------- |
| 柔柔#1716 | [Codepen](https://codepen.io/rouchen/pen/JjBXrjq?editors=0011) | | | |
| Bella_#1587 | [Codepen](https://codepen.io/Chen-Bella/pen/RwBaLNr) | | | |
| 楊苡安_#2752 | [hackmd](https://hackmd.io/@L7K9-66lSeagS28AP0_GjQ/Hk7T-AiFo) | | | |
| kuku#3118 | [Codepen](https://codepen.io/mengting-ku/pen/yLqOzGw) | | | |
| How#5806 | [Codepen](https://codepen.io/howtobefine/pen/ZEjWrWq) | | | |
| SASIMI#5099 | [Codepen](https://codepen.io/sashimi1327/pen/wvxGmMY) | | | |
| Knock59487#9114 | [Codepen](https://codepen.io/Zack88/pen/eYjZLVy?editors=1111) | | | |
| shiuan#4721 | [Codepen](https://codepen.io/prankaChang/pen/rNreqyP?editors=0011) | | | |
| FiReBrO #0557 | [Codepen](https://codepen.io/firebro42/pen/qByZwyL) | | | |
| Ron Liang#7277 | [Codepen](https://codepen.io/ron-go/pen/VwBaovG) | | | |
| 阿鑫#4346 | [CodePen](https://codepen.io/Neil1024/pen/eYjzNmK?editors=0011) | | | |
| PayRoom#8328 | [CodePen](https://codepen.io/water38198/pen/ZEjOGMw) | | | |
| sophiee#7015 | [codepen](https://codepen.io/sophiee2727/pen/qByNaKJ?editors=1011) | | | |
| Hironaka#7367 | [codepen](https://codepen.io/Hironaka0815/pen/rNrevvd?editors=0011) | | | |
| yoyo#1003 | [codepen](https://codepen.io/pen/WNKxpRQ) | | | |
| 你看我像是會玩嗎#1866 | [codepen](https://codepen.io/hasagg/pen/WNKxEXr) | | Yuna Huang#2692 | [codepen](https://codepen.io/Yuna1002/pen/XWBKgGN?editors=0011) |
| 阿沁#8176 | [CodePen](https://codepen.io/a8322342/pen/yLqJQdN) | | | |
| Hazel.#6020 | [CodePen](https://codepen.io/Hazelhsieh/pen/WNKrZXa) | | | |
| kevin#6131 | [CodePen](https://codepen.io/xlqjezvc-the-encoder/pen/wvxWNNP?editors=0011) | | | |
| Bassjim#0118 | [CodePen](https://codepen.io/unrtxbaq/pen/rNrMBqo?editors=1111) | | | |
| 竹輪#3335 | [CodePen](https://codepen.io/chikuwa0120/pen/jOpMOpR) | | | |
| 阿異#4776 | [Codepen](https://codepen.io/yani21399/pen/VwBKWEz) | | | |
|Wei#2330|[Codepen](https://codepen.io/ixfjxrbo-the-typescripter/pen/BaPQREp)|
|popcorn_3q#9893|[Codepen](https://codepen.io/arnyrpqt-the-sasster/pen/oNMBopg)|
|Shuo#1596|[Codepen](https://codepen.io/chiangchungshuo/pen/OJwWOoj)|
| Jenny真#7532 | [CodePen](https://codepen.io/wei-chen-wu/pen/xxJgaag?editors=0010) |
| 艸良#2846 | [CodePen](https://codepen.io/momoninainai/pen/dyjvpRN?editors=1010) |
| YI#0863 | [CodePen](https://codepen.io/YI0305/pen/YzjZZeQ?editors=0010) |
|MengLin#3001|[CodePen](https://codepen.io/aacj2642/pen/KKBWmja?editors=0012)|
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|Judy Wei#6103|[Codepen](https://codepen.io/Judy0718/pen/xxJdjNZ)|
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| YU#0618 | [Codepen](https://codepen.io/yoken_/pen/wvxeoNZ) |
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