how to loop and group value by checking whether key present or not in array of object

I have data like below

[
    {
        "time": 0,
    },
    {
        "endTime": 4.5,
        "time": 4,
    },
    {
        "time": 5,
    },
    {
        "endTime": 7,
        "time": 6,
    },
    {
        "endTime": 10,
        "time": 8,
    },
    {
        "endTime": 15,
        "time": 11,
    },
]

some have time only and some have time and endTime both

the output expecting was:
result : [0, 4.5, 5, 7, 8, 10, 11, 15]

i.e

• if only time there it should be pushed to odd index in array i.e 0 and 5
• if it has time and endTime and last result array length is odd, endTime should be pushed i.e 4.5 and 7
• if last result length is even and object have both time and endTime then both values should be added in order i.e time=8 and then endTime=10, 11 and then 15 must be pushed to array.

I tried something like below not working

let arrayOfSliderStartEndTime = arr.reduce((pv, cv, i) => {
        if(!("endTime" in cv)) pv.res.push(cv.time)
        else if("endTime" in cv) {
            if(pv.res.length%2 != 0) pv.res.push(cv.time)
            pv.res.push(cv.endTime)
        }

>Solution :

Check the below code.

let arr = [
    { "time": 0 },
    { "endTime": 4.5, "time": 4 },
    { "time": 5 },
    { "endTime": 7, "time": 6 },
    { "endTime": 10, "time": 8 },
    { "endTime": 15, "time": 11 },
];

let arrayOfSliderStartEndTime = arr.reduce((pv, cv, i) => {
    if (!("endTime" in cv)) {
        pv.res.push(cv.time);
    } else {
        if (pv.res.length % 2 !== 0) {
            pv.res.push(cv.endTime);
        } else {
            pv.res.push(cv.time, cv.endTime);
        }
    }
    return pv;
}, { res: [] }).res;

console.log(arrayOfSliderStartEndTime);