title: Display related Weeks in Second Drop down
body: <p>I just create two drop down , first is month drop down , I want to display second drop down of weeks.
  I try this code but fail.</p>
  
  <pre class="lang-js prettyprint-override"><code>weeklist: string[] = [];
  getWeeksInMonth(month, year) {
    var lenweek = [],
      week = [],
      firstDate = new Date(year, month, 1),
      lastDate = new Date(year, month + 1, 0),
      numDays = lastDate.getDate();
    var start = 1;
    var end = 7 - firstDate.getDay();
    while (start &lt;= numDays) {
      week.push({
        start,
        end
      });
      lenweek.push("Week" + week.length);
      start = end + 1;
      end = end + 7;
      if (end &gt; numDays)
        end = numDays;
    }
    this.weeklist = lenweek;
  }
  </code></pre>
  
  <pre class="lang-html prettyprint-override"><code>&lt;select class="weeks" #months (change)="addmonth(months.value)"&gt;
    &lt;option&gt;Select Month&lt;/option&gt;
    &lt;option *ngFor="let month of monthlist" [value]="month.count"&gt;
      {{ month.name }}
    &lt;/option&gt;
  &lt;/select&gt;
  
  &lt;span&gt;Select Week&lt;/span&gt; &lt;br&gt;
  &lt;select class="weeks" #weeks (change)="addweeks(weeks.value)"&gt;
    &lt;option *ngFor="let week of weeklist" [value]="week"&gt;
      {{ week }}
    &lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  
  
  <p>Result for january </p>
  
  <p><img src="https://i.stack.imgur.com/816V4.png" alt=""></p>
  
  <p>This result is same for all month.</p>
  
  <p>Result for april</p>
  
  <p><img src="https://i.stack.imgur.com/N0hgv.png" alt=""></p>
  
  <p>I Want Result Different Like For january Week1 to week5
  Feb Week6 to Week 10 ,Mar Week 11 to Week 15 , upto December..Week 52,</p>
  
  <p>Is this possible??</p>