1.数组扁平化
下面的数据多层树状结构处理成只有一层children的结构
data = [
{
name: "About",
path: "/about",
children: [
{
name: "About US",
path: "/about/us"
},
{
name: "About Comp",
path: "/about/company",
children: [
{
name: "About Comp A",
path: "/about/company/A",
children: [
{
name: "About Comp A 1",
path: "/about/company/A/1"
}
]
}
]
}
]
}
]
// 处理后的结构
[
{
name: "About",
path: "/about",
children: [
{
name: "About US",
path: "/about/us"
},
{
name: "About Comp",
path: "/about/company",
},
{
name: "About Comp A",
path: "/about/company/A"
},
{
name: "About Comp A 1",
path: "/about/company/A/1"
}
]
}
]
代码实现:
//递归遍历实现
var recursiveFunction3 = function(){
var aa=[]
var cc=[]
const getStr = function(data){
data.forEach(item => {
aa.push({
name: item.name,
path: item.path
})
if(item.children?.length){
let children=getStr(item.children)
}
})
}
getStr(data)
cc.push({
name: aa[0].name,
path: aa[0].path,
children:aa.slice(1)
})
// console.log(cc)
}
recursiveFunction3()
代码基于上个基础优化:
var recursiveFunction4 = function(){
var aa=[]
const getStr = function(data){
data.forEach(item => {
aa.push({
name: item.name,
path: item.path
})
if(item.children?.length){
let children=getStr(item.children)
}
})
}
getStr(data[0].children)
//...展开运算符 因为前两项数据没变直接拿来用了拷贝 然后把最后一项children替换掉
aa= [{...data[0],children:aa}]
console.log(aa)
}
recursiveFunction4()//基于recursiveFunction3()优化
还有一种方案借鉴大佬的,代码如下:
//写了一个可自由定义扁平化层级的代码,level代码不扁平的层级
function flatTree(data, level = 0, index = 0){
let result = [], obj;
data.forEach(item => {
result.push(obj = {
name: item.name,
path: item.path
})
if(item.children?.length){
let children = flatTree(item.children, level, index + 1)
if(level > index){
obj.children = children
}else{
result = result.concat(children)
}
}
})
return result
}
降维数组
//利用[].concat.apply实现降维
var arr=[[1,2],[3,4]];
function Jw(obj){
console.log(Array.prototype.concat.apply([],obj))
return Array.prototype.concat.apply([],obj);
}
Jw(arr);
//如果concat方法的参数是一个元素,该元素会直接插入新数组中;如果参数是一个数组,该数组的各个元素将被插入到新数组中
function reduceDimension(arr){
let ret = [];
for(let i=0;i<arr.length;i++){
ret=ret.concat(arr[i])
}
console.log(ret)
return ret;
}
reduceDimension(arr)
//递归
function reduceDimension(arr){
let ret = [];
let toArr = function(arr){
arr.forEach(function(item){
item instanceof Array ? toArr(item) : ret.push(item);
});
}
toArr(arr);
console.log(ret)
return ret;
}
reduceDimension([1, 2, [3, 4, [5, 6]]])
//flat
let list = [1, 2, 3, [4, [5]]];
let res = list.flat(Infinity)
console.log(res) // [1, 2, 3, 4, 5]
排序
升序降序排序函数sortNumber
const arr1 = [6,1,2,3,4];
function sortNumber(a,b){
return b-a;
}
arr1.sort(sortNumber);
console.log(arr1)// [6, 4, 3, 2, 1]
按照flag排序,为true的在前面显示
//其实这个和上边的原理是一样的等同,只是简写了
const arr2 = [
{ id: 10, flag: true },
{ id: 5, flag: false },
{ id: 6, flag: true },
{ id: 9, flag: false }
];
const r = arr2.sort((a, b) => b.flag - a.flag);
console.log(r);
// [
// { id: 10, flag: true },
// { id: 6, flag: true },
// { id: 5, flag: false },
// { id: 9, flag: false }
// ]
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