function mergeJSON(o, n) {
    let oType = Object.prototype.toString.call(o);
    let nType = Object.prototype.toString.call(n);
    if (nType == '[object Object]' && oType == '[object Object]') {
        //合并属性(object)
        for (let p in n) {
            if (n.hasOwnProperty(p) && !o.hasOwnProperty(p)) {
                o[p] = n[p];
            } else if (n.hasOwnProperty(p) && (o.hasOwnProperty(p))) {
                let oPType = Object.prototype.toString.call(o[p]);
                let nPType = Object.prototype.toString.call(n[p]);
                if ((nPType == '[object Object]' && oPType == '[object Object]') || (nPType == '[object Array]' && oPType == '[object Array]')) {
                    mergeJSON(o[p], n[p]);
                } else {
                    o[p] = n[p];
                }
            }
        }
    } else if (nType == '[object Array]' && oType == '[object Array]') {
        //合并属性(array)
        for (let i in n) {
            let oIType = Object.prototype.toString.call(o[i]);
            let nIType = Object.prototype.toString.call(n[i]);
            if ((nIType == '[object Object]' && oIType == '[object Object]') || (nIType == '[object Array]' && oIType == '[object Array]')) {
                mergeJSON(o[i], n[i]);
            } else {
                o[i] = n[i];
            }
        }
    }

    //合并属性(other)
    o = n;
}

//test

let json1={
    "a": "json1", 
    "b": 123, 
    "c": {
        "dd": "json1 dd", 
        "ee": 556, 
        "f": "ff1"
    }, 
    "list": [
        {
            "a": 123, 
            "b": 96
        }, 
        {
            "a": 45, 
            "b": 56
        }
    ]
};
let json2={

    "a": "json2", 
    "a2": 369, 
    "c": {
        "dd2": "json2 dd", 
        "ee": "gg2"
    }, 
    "list": [
        {
            "a": "a1", 
            "b1": 69
        }, 
        369, 
        {
            "i3": 36
        }
    ]
};

mergeJSON(json1,json2);

console.log(JSON.stringify(json1));