Javascript 如何按区域进行过滤并将其从结果数组中删除

我有以下数组 struct :

const values = [{
    "region": "US", "content": "content 1", "value": "value1"
}, {
    "region": "US", "content": "content 2", "value": "value2"
}, {
    "region": "US", "content": "content 3", "value": "value3"
}, {
    "region": "LA", "content": "content 4", "value": "value4"
}, {
    "region": "LA", "content": "content 5", "value": "value5"
}, {
    "region": "LA", "content": "content 6", "value": "value6"
}, {
    "region": "LA", "content": "content 7", "value": "value7"
}]

我正在try 将其转换为以下内容-请注意，在输出数组内的结果对象中没有region键:

const output = [{
    "US": [
        {"content": "content 1", "value": "value1"},
        {"content": "content 2", "value": "value2"},
        {"content": "content 3", "value": "value3"}
    ],
    "LA": [
        {"content": "content 4", "value": "value4"},
        {"content": "content 5", "value": "value5"},
        {"content": "content 6", "value": "value6"},
        {"content": "content 7", "value": "value7"}
    ]
}]

到目前为止，这是我try 过的:

let outputValues = [];

values.forEach(currentElement => {
    outputValues[currentElement.region].push(currentElement);
})

console.log(outputValues);

上面的解决方案给出了以下错误:

未捕获的TypeError:无法读取未定义的属性(正在读取‘Push’)

不知道为什么.

我也try 过:

# 1st option
outputValues[currentElement.region] = currentElement;

# 2nd option
outputValues[currentElement.region] = [];
outputValues[currentElement.region].push(currentElement);

但这只添加了主values数组中的最后一个元素.我错过了什么吗？