javascript - Filter Array in Array by date between 2 dates

Question

I am trying to filter a data-array of a LineChart by the from-date / to-date input of a user in TypeScript for my Angular App. The data array has the following structure:

var multi = [
    {
      "name": "test1",
      "series": [
        {
            "date": new Date("2018-01-01T01:10:00Z"),
            "value": 44
        },...
      ]
    },
    {
      "name": "test2",
      "series": [
        {
            "date": new Date("2018-01-01T01:10:00Z"),
            "value": 38
          },...
      ]
    },
    {
      "name": "test3",
      "series": [
        {
            "date": new Date("2018-01-01T01:10:00Z"),
            "value": 33
          },...
      ]
    }
  ];

I now want to filter the items of the array by the criteria that the date inside is after a 'fromDate' and before a 'toDate'. I tried the following:

obj.forEach(data => {
            console.log(data.name);
            data.series = data.series.filter((item: any) => {
                item.date.getTime() >= fromDate.getTime() &&
                item.date.getTime() <= toDate.getTime();
            });
        });

the obj[] array has an empty obj[i].series array afterwards. Can anybody help me here? The iteration seems to be right since debugging gave me all the dates, also the true/False statements from the date comparing was right as well.

Thanks in advance

Answer 1

You need to return the compairing value, either explicit

data.series = data.series.filter((item: any) => {
    return item.date.getTime() >= fromDate.getTime() &&
           item.date.getTime() <= toDate.getTime();
});

or without the brackets, implicit.

data.series = data.series.filter((item: any) =>
    item.date.getTime() >= fromDate.getTime() && item.date.getTime() <= toDate.getTime()
);