假设我们有两个JSON数组：array1和array2。需要按照元素"key"合并它们，如果不存在，则添加新的字段"newField"。

代码示例：

const array1 = [{ "key": 1, "value1": "a" }, { "key": 2, "value1": "b" }]; const array2 = [{ "key": 1, "value2": "c" }, { "key": 3, "value2": "d" }];

const mergedArray = array1.map((item1) => { const item2 = array2.find((item2) => item1.key === item2.key); if (item2) { return { ...item1, ...item2 }; } return { ...item1, newField: "new value" }; });

console.log(mergedArray);

输出结果为：

[ { "key": 1, "value1": "a", "value2": "c" }, { "key": 2, "value1": "b", "newField": "new value" }, { "key": 3, "value2": "d", "newField": "new value" } ]