title: Filter Array in Array by date between 2 dates
body: <p>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:</p>
  
  <pre><code>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
            },...
        ]
      }
    ];
  </code></pre>
  
  <p>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: </p>
  
  <pre><code>obj.forEach(data =&gt; {
              console.log(data.name);
              data.series = data.series.filter((item: any) =&gt; {
                  item.date.getTime() &gt;= fromDate.getTime() &amp;&amp;
                  item.date.getTime() &lt;= toDate.getTime();
              });
          });
  </code></pre>
  
  <p>the <code>obj[]</code> array has an empty <code>obj[i].series</code> 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. </p>
  
  <p>Thanks in advance</p>