深度优先DFS和广度优先BFS遍历

一般用于dom树的或树形菜单的结构

let tree=[
    {
    children:[
        {
            children:[
                {
                    children:[
                        'a',
                        {children:'b'}
                    ]
                },
                {
                    children:'c'
                }
            ]
        },
        {children:[{children:['d',{children:'e'}]},{children:'f'}]},
        {children:[0]}
        ]
    }
]

深度优先

//递归
function deepFirst(tree){
    let res=[];
    function deepIn(tree){
        if(tree&&Array.isArray(tree)){
            for(let i=0;i<tree.length;i++){
                if(tree[i].children){
                    deepIn(tree[i].children)
                }else{
                    res.push(tree[i]) 
                }
            }
        }else{
            res.push(tree)
        }
    }
    deepIn(tree);
    return res
}

//非递归
function deepFirst(tree){
    let res=[];
    let temp=tree;
    while(temp.length){
        let item=temp.pop();
        if(item.children){
            for(let i= item.children.length-1;i>=0;i--){
                temp.push(item.children[i])
            }
        }else{
            res.push(item);
        }
    }
    return res;
}

广度优先

//非递归实现
function breadthFirst(tree){
    let temp=tree;
    let res=[];
    while(temp.length){
        if(temp[0].children){
            Array.isArray(temp[0].children)?temp.push(...temp[0].children):temp.push(temp[0].children)
        }else{
            res.push(temp[0])
        }
        temp.shift();
    }
    return res;
}