From 82abddab67d18a6da4c225af7e8abdc280620286 Mon Sep 17 00:00:00 2001
From: xuwu <zx597813039@gmail.com>
Date: Thu, 25 Mar 2021 08:04:50 +0800
Subject: [PATCH] =?UTF-8?q?docs:=20=E7=AC=AC=E5=85=AD=E9=A2=98=E7=AD=94?=
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+```js
+/**
+ * @param input
+ * @param size
+ * @returns {Array}
+ */
+_.chunk(['a', 'b', 'c', 'd'], 2)
+// => [['a', 'b'], ['c', 'd']]
+
+_.chunk(['a', 'b', 'c', 'd'], 3)
+// => [['a', 'b', 'c'], ['d']]
+
+_.chunk(['a', 'b', 'c', 'd'], 5)
+// => [['a', 'b', 'c', 'd']]
+
+_.chunk(['a', 'b', 'c', 'd'], 0)
+// => []
+```
+
+这道题目其实就是让大家实现一个 lodash 里的函数，这边我们需要注意的一个点是不能更改原数组，虽然题目没有提到，但是我们得想到这个。
+
+笔者这里推荐几个答案，分别是不同的写法，难度从低到高吧。
+
+首先是遍历的写法：
+
+[答案链接](https://github.com/KieSun/fucking-frontend/issues/8#issuecomment-799053150)
+
+```js
+function chunk(arr, num) {
+  if (num === 0) return [];
+  if (Array.isArray(arr) && typeof num === "number") {
+    let result = [];
+    let i = 0;
+    while (i < arr.length) {
+      result.push(arr.slice(i, i + num));
+      i += num;
+    }
+    return result;
+  } else {
+    console.log("params type error");
+  }
+}
+```
+
+我们也可以使用 `reduce` 来解题：
+
+[答案链接](https://github.com/KieSun/fucking-frontend/issues/8#issuecomment-799021398)
+
+```js
+const chunk = (arr, len) => arr.reduce((pre, cur, index) => {
+  if (index % len === 0) {
+    pre.push([cur])
+    return pre
+  }
+  const temp = pre[pre.length - 1]
+  temp && temp.push(cur)
+  return pre
+}, [])
+```
+
+甚至直接优化到一行：
+
+[答案链接](https://github.com/KieSun/fucking-frontend/issues/8#issuecomment-799344324)
+
+```js
+function chunk(arr, size){
+  return Array.from({length: (size = Number.parseInt(size)) ? Math.ceil(arr.length/size) : 0})
+    .map((a,i) => arr.slice(i*size, (i+1)*size))
+}
+```