这次给大家带来js数值类型数组去重，js数值类型数组去重的注意事项有哪些，下面就是实战案例，一起来看一下。
前言
本文主要介绍了关于js构建二叉树进行数值数组的去重与优化的相关内容，分享出来供大家参考学习，下面话不多说了，来一起看看详细的介绍吧。
常见两层循环实现数组去重
let arr = [11, 12, 13, 9, 8, 7, 0, 1, 2, 2, 5, 7, 11, 11, 7, 6, 4, 5, 2, 2]let newarr = []for (let i = 0; i < arr.length; i++) { let unique = true for (let j = 0; j < newarr.length; j++) { if (newarr[j] === arr[i]) { unique = false break } } if (unique) { newarr.push(arr[i]) }}console.log(newarr)
构建二叉树实现去重（仅适用于数值类型的数组）
将先前遍历过的元素，构建成二叉树，树中每个结点都满足：左子结点的值 < 当前结点的值 < 右子结点的值
这样优化了判断元素是否之前出现过的过程
若元素比当前结点大，只需要判断元素是否在结点的右子树中出现过即可
若元素比当前结点小，只需要判断元素是否在结点的左子树中出现过即可
let arr = [0, 1, 2, 2, 5, 7, 11, 7, 6, 4,5, 2, 2]class node { constructor(value) { this.value = value this.left = null this.right = null }}class binarytree { constructor() { this.root = null this.arr = [] } insert(value) { let node = new node(value) if (!this.root) { this.root = node this.arr.push(value) return this.arr } let current = this.root while (true) { if (value > current.value) {    if (current.right) {     current = current.right    } else {     current.right = node     this.arr.push(value)     break    }   }   if (value < current.value) { if (current.left) { current = current.left } else { current.left = node this.arr.push(value) break } } if (value === current.value) { break } } return this.arr }}let binarytree = new binarytree()for (let i = 0; i < arr.length; i++) { binarytree.insert(arr[i])}console.log(binarytree.arr)
优化思路一，记录最大最小值
记录已经插入元素的最大最小值，若比最大元素大，或最小元素小，则直接插入
let arr = [11, 12, 13, 9, 8, 7, 0, 1, 2, 2, 5, 7, 11, 11, 7, 6, 4, 5, 2, 2]class node { constructor(value) { this.value = value this.left = null this.right = null }}class binarytree { constructor() { this.root = null this.arr = [] this.max = null this.min = null } insert(value) { let node = new node(value) if (!this.root) { this.root = node this.arr.push(value) this.max = value this.min = value return this.arr } if (value > this.max) {   this.arr.push(value)   this.max = value   this.findmax().right = node   return this.arr  }  if (value < this.min) { this.arr.push(value) this.min = value this.findmin().left = node return this.arr } let current = this.root while (true) { if (value > current.value) {    if (current.right) {     current = current.right    } else {     current.right = node     this.arr.push(value)     break    }   }   if (value < current.value) { if (current.left) { current = current.left } else { current.left = node this.arr.push(value) break } } if (value === current.value) { break } } return this.arr } findmax() { let current = this.root while (current.right) { current = current.right } return current } findmin() { let current = this.root while (current.left) { current = current.left } return current }}let binarytree = new binarytree()for (let i = 0; i < arr.length; i++) { binarytree.insert(arr[i])}console.log(binarytree.arr)
优化思路二，构建红黑树
构建红黑树，平衡树的高度
有关红黑树的部分，请见红黑树的插入
let arr = [11, 12, 13, 9, 8, 7, 0, 1, 2, 2, 5, 7, 11, 11, 7, 6, 4, 5, 2, 2]console.log(array.from(new set(arr)))class node { constructor(value) { this.value = value this.left = null this.right = null this.parent = null this.color = 'red' }}class redblacktree { constructor() { this.root = null this.arr = [] } insert(value) { let node = new node(value) if (!this.root) { node.color = 'black' this.root = node this.arr.push(value) return this } let cur = this.root let inserted = false while (true) { if (value > cur.value) {    if (cur.right) {     cur = cur.right    } else {     cur.right = node     this.arr.push(value)     node.parent = cur     inserted = true     break    }   }   if (value < cur.value) { if (cur.left) { cur = cur.left } else { cur.left = node this.arr.push(value) node.parent = cur inserted = true break } } if (value === cur.value) { break } } // 调整树的结构 if(inserted){ this.fixtree(node) } return this } fixtree(node) { if (!node.parent) { node.color = 'black' this.root = node return } if (node.parent.color === 'black') { return } let son = node let father = node.parent let grandfather = father.parent let directionftog = father === grandfather.left ? 'left' : 'right' let uncle = grandfather[directionftog === 'left' ? 'right' : 'left'] let directionstof = son === father.left ? 'left' : 'right' if (!uncle || uncle.color === 'black') { if (directionftog === directionstof) { if (grandfather.parent) { grandfather.parent[grandfather.parent.left === grandfather ? 'left' : 'right'] = father father.parent = grandfather.parent } else { this.root = father father.parent = null } father.color = 'black' grandfather.color = 'red' father[father.left === son ? 'right' : 'left'] && (father[father.left === son ? 'right' : 'left'].parent = grandfather) grandfather[grandfather.left === father ? 'left' : 'right'] = father[father.left === son ? 'right' : 'left'] father[father.left === son ? 'right' : 'left'] = grandfather grandfather.parent = father return } else { grandfather[directionftog] = son son.parent = grandfather son[directionftog] && (son[directionftog].parent = father) father[directionstof] = son[directionftog] father.parent = son son[directionftog] = father this.fixtree(father) } } else { father.color = 'black' uncle.color = 'black' grandfather.color = 'red' this.fixtree(grandfather) } }}let redblacktree = new redblacktree()for (let i = 0; i < arr.length; i++) { redblacktree.insert(arr[i])}console.log(redblacktree.arr)
其他去重方法
通过 set 对象去重
[...new set(arr)]
通过 sort() + reduce() 方法去重
排序后比较相邻元素是否相同，若不同则添加至返回的数组中
值得注意的是，排序的时候，默认 compare(2, '2') 返回 0；而 reduce() 时，进行全等比较
let arr = [0, 1, 2, '2', 2, 5, 7, 11, 7, 5, 2, '2', 2]let newarr = []arr.sort((a, b) => { let res = a - b if (res !== 0) {  return res } else {  if (a === b) {   return 0  } else {   if (typeof a === 'number') {    return -1   } else {    return 1   }  } }}).reduce((pre, cur) => { if (pre !== cur) {  newarr.push(cur)  return cur } return pre}, null)
通过 includes() + map() 方法去重
let arr = [0, 1, 2, '2', 2, 5, 7, 11, 7, 5, 2, '2', 2]let newarr = []arr.map(a => !newarr.includes(a) && newarr.push(a))
通过 includes() + reduce() 方法去重
let arr = [0, 1, 2, '2', 2, 5, 7, 11, 7, 5, 2, '2', 2]let newarr = arr.reduce((pre, cur) => {  !pre.includes(cur) && pre.push(cur)  return pre}, [])
通过对象的键值对 + json 对象方法去重
let arr = [0, 1, 2, '2', 2, 5, 7, 11, 7, 5, 2, '2', 2]let obj = {}arr.map(a => {  if(!obj[json.stringify(a)]){    obj[json.stringify(a)] = 1  }})console.log(object.keys(obj).map(a => json.parse(a)))
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以上就是js数值类型数组去重的详细内容。