/**
 * 根據key找value：當key都是唯一、不會重複的時候
 * @param jsonData：json資料
 * @param pathArr：路徑(帶父級)，如：girlfriend.age
 * @return {Array}
 */
function getValueByKey (data, field) {
    for (let key in data) {
        if (key === field) {
            return data[key];
        }
        if (typeof(data[key]) === 'object'
 
 && data[key].length === undefined) {
            return getValueByKey(data[key], textField);
        } 
    }
}

var jsonObj = {
    "中國": {
        "北京": [
            "朝陽"
        ],
        "廣州": [
            "天河"
        ]
    },
    "美國": {},
    "英國": [
        "愛爾蘭"
    ]
}

var result = getValueByKey(jsonObj, '廣州'
 
);
console.log(result);  //['天河']

/**
 * 根據key的路徑找value
 * @param jsonData：json資料
 * @param pathArr：路徑(帶父級)，如：girlfriend.age
 * @return {Array}
 */
 function getValueByKey(jsonData, pathArr) {
    var values = [];

    for (var idx in pathArr) {
        var valueJson = {};
        valueJson.path = pathArr[idx];

        var
 
 keyArr = pathArr[idx].split(".");

        var value = jsonData;

        for (var i in keyArr) {
            value = value[keyArr[i]];
        }

        valueJson.value = value;
        values.push(valueJson);

    }
    return values;
}

var jsonData = {
    name: 'simet',
    age: 22,
    girlfriend: {
        name: 'betty',
        age: 21,

    }
};

var cc = getValueByKey(jsonData, ['girlfriend.age', 'age']);
console.log(cc);

/**
 * 獲取json的所有key
 * @param jsonObj：json值
 * @param parentPath
 * @return {Array}
 */
function getKeyAndPath(jsonObj, parentPath) {
    var keyJsonArr = [];
    var space = '';
    if (parentPath != null) {
        for (var i = 0; i < parentPath.split('.').length; i++) {
            space = space + ' ';
        }
    }
    for (var key in jsonObj) {
        var path;
        if (parentPath == null) {
            path = key;
        } else {
            path = parentPath + '.' + key;
        }
        var keyJsonObj = {};
        keyJsonObj.key = key;
        keyJsonObj.newKey = space + key;
        keyJsonObj.path = path;
        keyJsonArr.push(keyJsonObj);
        if (typeof (jsonObj[key]) == 'object' && jsonObj[key].length == undefined) {
            keyJsonArr = keyJsonArr.concat(getKeyAndPath(jsonObj[key], path));
        }
    }
    return keyJsonArr;
}
var aaaaa = getKeyAndPath(jsonData);
console.log(aaaaa);