每日学习

deepclone.js

@@ -0,0 +1,38 @@
+function _type(value) {
+  return Object.toString.call(value).slice(8,-1).toLocaleLowerCase()
+}
+
+function deepclone(obj) {
+  if(obj === null) return null
+  if(typeof obj !== 'object') return obj
+  if(_type(obj) === 'regexp') return new RegExp(obj)
+  if(_type(obj) === 'date') return new Date(obj)
+  const newObj = new obj.constructor
+  for(const key in obj) {
+    if(obj.hasOwnProperty(key)) {
+      let item = obj[key]
+      newObj[key] = deepclone(item)
+    }
+  }
+  return newObj
+}
+
+function deepclone2(obj) {
+  if(typeof obj !== 'object' || obj === null) return
+  let newObj = new obj.constructor
+  for(let key in obj) {
+    if(obj.hasOwnProperty(key)) {
+      let item = obj[key],itemType = _type(item)
+      if(item !== null && typeof item === 'object') {
+        if(/(regexp|date)/.test(itemType)) {
+          newObj[key] = new item.constructor(item)
+          continue
+        }
+        newObj[key] = deepclone2(item)
+        continue
+      }
+      newObj[key] = item
+    }
+    return newObj
+  }
+}

promise.js

@@ -0,0 +1,63 @@
+const PENDING = 'pending'
+const RESOLVED = 'resolved'
+const REJECTED = 'rejected'
+
+class MyPromise {
+  constructor(fn) {
+    this.state = PENDING
+    //终值
+    this.value = null
+    //拒因
+    this.reason = null
+    //成功回调队列
+    this.onResolvedCbs = []
+    //拒绝回调队列
+    this.onRejectedCbs = []
+
+    const resolve = value => {
+      setTimeout(() => {
+        if(this.state === PENDING) {
+          this.state = RESOLVED
+          this.value = value
+          this.onResolvedCbs.map(cb => {
+            this.value = cb(this.value)
+          })
+        }
+      })
+    }
+
+    const reject = reson => {
+      setTimeout(() => {
+        if(this.state === PENDING) {
+          this.state = REJECTED
+          this.reason = reson
+          this.onRejectedCbs.map(cb => {
+            this.reason = cb(this.reason)
+          })
+        }
+      })
+    }
+    try {
+      fn(resolve, reject)
+    } catch(e) {
+      reject(e)
+    }
+  }
+
+  then(onResolved, onRejected) {
+    typeof onResolved === 'function' && this.onResolvedCbs.push(onResolved)
+    typeof onRejected === 'function' && this.onRejectedCbs.push(onRejected)
+    return this
+  }
+}
+
+new MyPromise((resolve,reject) => {
+  setTimeout(() => {
+    resolve(2)
+  },1000)
+}).then(res => {
+  console.log(res)
+  return res + 1
+}).then(res => {
+  console.log(res)
+})