I've got an array of times in epoch like below:

const times = [1653931370, 1653924170, 1653920570, 1653913370, 1653913370, 1653902570]

all of this dates is from one single day between 00:00 and 23:59. Right now i need to assign each of these times to a specific hour along with the number of occurrences of that hour. My response should be like below:

[
    {
        hour: 0, //00:00
        occurs: 4
    },
    {
        hour: 1, //01:00
        occurs: 4
    },

    ...

    {
        hour: 22, //22:00
        occurs: 17
    },
    {
        hour: 23, //23:00
        occurs: 12
    },
]

can someone help me with this issue? Thanks for any help!

CodePudding user response：

1. Map over the array and get the hours using the Date.prototype.getHours method.

2. Then group the hours using Array.prototype.reduce.

const times = [
  1653931370, 1653924170, 1653920570, 1653913370, 1653913370, 1653902570,
];

const res = Object.values(
  times
    .map((t) => new Date(t * 1000).getHours())
    .reduce((r, t) => {
      r[t] ??= { hour: t, occurs: 1 };
      r[t].occurs  = 1;
      return r;
    }, {})
);

console.log(res);

Other relevant documentations:

• Array.prototype.map
• Object.values
• Nullish coalescing operator (??)

CodePudding user response：

Create new object. Loop over all times, for example with for each. Use Date class like this new Date(epoch * 1000).getHours() and store that time. Check if key your_hour exists on new object. If it doesn't, push it like myResult[your_hour] = {hour: your_hour, occurances: 1}. If it does exist, then add to that object like so myResult[your_hour].occurances = myResult[your_hour].occurances 1;. That's usually the approach I use but there's multiple solutions to this.