update docs

src/docs/blog/4.md

@@ -489,3 +489,69 @@ function myReduce(arr, cb, initialValue) {
 const arr = [1, 2, 3, 4, 5]
 console.log(myReduce(arr, (a, b) => a + b)) // 15
 ```
+
+## Array.prototype.reduceRight()
+
+```js
+function myReduceRight(arr, cb, initialValue) {
+  const len = arr.length
+  let i = initialValue === undefined ? len - 2 : len - 1
+  initialValue = initialValue === undefined ? arr[len - 1] : initialValue
+  let accumulator = initialValue
+
+  for (; i >= 0; i--) {
+    accumulator = cb.call(undefined, accumulator, arr[i], arr)
+  }
+  return accumulator
+}
+
+// test
+const arr = [1, 2, 3, 4, 5]
+console.log(myReduceRight(arr, (a, b) => a + b)) // 15
+```
+
+## Array.prototype.reverse()
+
+```js
+function myReverse(arr) {
+  const len = arr.length
+  const res = []
+
+  for (let i = len - 1; i >= 0; i--) {
+    res[res.length] = arr[i]
+  }
+
+  for (let i = 0; i < len; i++) {
+    arr[i] = res[i]
+  }
+
+  return arr
+}
+
+// test
+const arr = [1, 2, 3, 4, 5]
+myReverse(arr)
+console.log(arr) // [5, 4, 3, 2, 1]
+```
+
+## Array.prototype.shift()
+
+```js
+function myShift(arr) {
+  const len = arr.length
+  const res = arr[0]
+
+  for (let i = 1; i < len; i++) {
+    arr[i - 1] = arr[i]
+  }
+
+  arr.length = len - 1
+
+  return res
+}
+
+// test
+const arr = [1, 2, 3, 4, 5]
+console.log(myShift(arr)) // 1
+console.log(arr) // [2, 3, 4, 5]
+```