javascript - masalah tatasusunan pelbagai dimensi js

Question

[
    {
        "id": 1,
        "name": "sys",
        "title": "系统设置",
        "type": 1,
        "status": 1,
        "condition": "",
        "pid": 0,
        "level": 0,
        "sort": 7,
        "icon": "fa-gear",
        "children": [
            {
                "id": 11,
                "name": "conf/lst",
                "title": "配置列表",
                "type": 1,
                "status": 1,
                "condition": "",
                "pid": 1,
                "level": 1,
                "sort": 50,
                "icon": null,
                "children": [
                    {
                        "id": 12,
                        "name": "conf/add",
                        "title": "添加配置",
                        "type": 1,
                        "status": 1,
                        "condition": "",
                        "pid": 11,
                        "level": 2,
                        "sort": 50,
                        "icon": null,
                        "children": []
                    },
                    {
                        "id": 13,
                        "name": "conf/del",
                        "title": "配置删除",
                        "type": 1,
                        "status": 1,
                        "condition": "",
                        "pid": 11,
                        "level": 2,
                        "sort": 50,
                        "icon": null,
                        "children": []
                    },
                    {
                        "id": 14,
                        "name": "conf/edit",
                        "title": "配置编辑",
                        "type": 1,
                        "status": 1,
                        "condition": "",
                        "pid": 11,
                        "level": 2,
                        "sort": 50,
                        "icon": null,
                        "children": []
                    }
                ]
            },
            {
                "id": 9,
                "name": "conf/conf",
                "title": "配置项",
                "type": 1,
                "status": 1,
                "condition": "",
                "pid": 1,
                "level": 1,
                "sort": 50,
                "icon": null,
                "children": []
            }
        ]
    },
    {
        "id": 15,
        "name": "admin",
        "title": "管理员",
        "type": 1,
        "status": 1,
        "condition": "",
        "pid": 0,
        "level": 0,
        "sort": 50,
        "icon": "fa-user",
        "children": [
            {
                "id": 16,
                "name": "admin/lst",
                "title": "管理员列表",
                "type": 1,
                "status": 1,
                "condition": "",
                "pid": 15,
                "level": 1,
                "sort": 50,
                "icon": null,
            },
            {
                "id": 27,
                "name": "authrule/lst",
                "title": "权限列表",
                "type": 1,
                "status": 1,
                "condition": "",
                "pid": 15,
                "level": 1,
                "sort": 50,
                "icon": null,
            },
            {
                "id": 30,
                "name": "authgroup/lst",
                "title": "用户组",
                "type": 1,
                "status": 1,
                "condition": "",
                "pid": 15,
                "level": 1,
                "sort": 50,
                "icon": null,
            }
        ]
    }
]

Json di atas ialah tatasusunan berbilang dimensi Saya ingin menggunakan js untuk gelung untuk mengeluarkan tatasusunan di bawah kanak-kanak, tetapi saya tidak tahu mengapa ia tidak boleh dikeluarkan dan tiada ralat dilaporkan

$.ajax({
    type: "get",
    url: "/admin/index/menu",
    async: true,
    dataType: 'json',
    success: function(res) {
        for(var i = 0; i < res.length; i++) {
            console.log(res[i].children);    //这个能输出
            for (var a=0;a<res[i].children;a++) {
                console.log(res[i].children[a]);    //这个不能输出,也没有报错
            }
        }
    }
})

Maaf, ada apa?

Answer 1

$.ajax({
    type: "get",
    url: "/admin/index/menu",
    async: true,
    dataType: 'json',
    success: function(res) {
        for(var i = 0; i < res.length; i++) {
            console.log(res[i].children);
            for (var a = 0; a < res[i].children.length; a++) { // <-- 此处少了.length，数字和对象比较大小，结果为false，第二个条件一次也满足不了
                console.log(res[i].children[a]);
            }
        }
    }
}

Answer 2

a<res[i].children -> a<res[i].children.length

Answer 3

Walaupun saya lambat, saya rasa saya boleh menambah sesuatu yang lain

Secara amnya, saya secara peribadi lebih suka menggunakan foreach traversal, dalam JS (ambil kod dalam contoh ini sebagai contoh)

res.forEach(r => {
    r.children.forEach(c => {
        // do something
    });
});

Fungsi anak panah es6 digunakan di atas Jika anda ingin menulisnya dalam es5, tukar sahaja kepada ekspresi fungsi

Answer 4

Ini seharusnya rekursi. Adalah disyorkan untuk memahami pengetahuan rekursi
Rekursif lintasan nod