How to add the value of a previous array item to the next item given that the key does not have a fixed name?

I have an array like so in order of date.

PLEASE NOTE that the category and total are FIXED. However the key VALUE series variable can be anything!!

let originalArray = [
    {
        "category": 1384473600000,
        "total": 1,
        "VALUE series variable": 100
    },
    {
        "category": 1384992000000,
        "total": 1,
        "VALUE series variable": 1000
    },
    {
        "category": 1499990400000,
        "total": 1,
        "VALUE series variable": 10
    },
    {
        "category": 1565654400000,
        "total": 1,
        "VALUE series variable": 542
    },
    {
        "category": 1568505600000,
        "total": 1,
        "VALUE series variable": 124
    }
]

How can I add the items of the key that is not ‘category’ or ‘total’ (so in this case its the key with name VALUE series variable) of the previous item to the next item?

I want to achieve the following:

let newArray = [
    {
        "category": 3456345634634,
        "total": 1,
        "VALUE series variable": 100,      // ORIGINAL 100 IS THE SAME
    },
    {
        "category": 1384992000000,
        "total": 1,
        "VALUE series variable": 1100,     // 100 + 1000 
    },
    {
        "category": "1499990400000",
        "total": 1,
        "VALUE series variable": 1110,     // 1100 + 10
    },
    {
        "category": "1565654400000",
        "total": 1,
        "VALUE series variable": 1652,      // 1110 + 542
    },
    {
        "category": "1568505600000",
        "total": 1,
        "VALUE series variable": 1776,       // 1652 + 124
    }
]

I know I can iterate through the original array like so and I can use .reduce to get the previous item:

originalArray.forEach(element => {
    element.
});

However,’VALUE series variable’ isn’t fixed and can be anything (e.g. the name of this key is random but consistent. All of the array items have the same key but the key is generated by the user. So I’m unsure how to go forwards and how to add the previous item to the next item.