SOURCE

function treeConvertToArr(arr) {
    let res = [];
    for (let i = 0; i < arr.length; i++) {
        if (arr[i].children) {
            res = res.concat(this.treeConvertToArr(arr[i].children));
            //删除父级的children属性，须保留children则把这行删除
            delete arr[i].children
        }
        res.push(arr[i]);
    }
    return res;
}
const jsdata = [
    {
        "parentName": null,
        "label": "合肥市",
        "value": "340100",
        "rawData": {
            "parentName": "",
            "name": "合肥市",
            "value": "340100"
        },
        "childOpen": true,
        "selected": false,
        "isSearch": false,
        "searchConnectives": "",
        "parantCode": [
            null
        ],
        "level": 0,
        "children": [
            {
                "parentName": "合肥市",
                "label": "瑶海区",
                "value": "340102",
                "rawData": {
                    "parentName": "合肥市",
                    "name": "瑶海区",
                    "value": "340102"
                },
                "childOpen": true,
                "selected": false,
                "isSearch": false,
                "searchConnectives": "",
                "parantCode": [
                    "合肥市"
                ],
                "level": 1,
                "children": [
                    {
                        "parentName": "瑶海区",
                        "label": "新站",
                        "value": "3401023",
                        "rawData": {
                            "parentName": "瑶海区",
                            "name": "新站",
                            "value": "3401023"
                        },
                        "childOpen": true,
                        "selected": false,
                        "isSearch": false,
                        "searchConnectives": "",
                        "parantCode": [
                            "瑶海区"
                        ],
                        "level": 2,
                        "children": [
                            {
                                "parentName": "新站",
                                "label": "磨店",
                                "value": "34010235",
                                "rawData": {
                                    "parentName": "新站",
                                    "name": "磨店",
                                    "value": "34010235"
                                },
                                "childOpen": false,
                                "selected": false,
                                "isSearch": false,
                                "searchConnectives": "",
                                "parantCode": [
                                    "新站"
                                ],
                                "level": 3
                            }
                        ]
                    }
                ]
            }
        ]
    }
]
console.log(treeConvertToArr(jsdata))