title: generate json array object or json object from angular material table
body: <p>Actually the requirement is to generate json array object or json object from angular material table so that I can use this object and export to Excel sheet.</p>
  
  <p>Below is the data.</p>
  
  <pre><code>const ELEMENT_DATA: Element[] = [
    {position: 1, name: 'Hydrogen', weight: 1.0079, symbol: 'H'},
    {position: 2, name: 'Helium', weight: 4.0026, symbol: 'He'},
    {position: 3, name: 'Lithium', weight: 6.941, symbol: 'Li'},
    {position: 4, name: 'Beryllium', weight: 9.0122, symbol: 'Be'},
    {position: 5, name: 'Boron', weight: 10.811, symbol: 'B'},
    {position: 6, name: 'Carbon', weight: 12.0107, symbol: 'C'},
    {position: 7, name: 'Nitrogen', weight: 14.0067, symbol: 'N'},
    {position: 8, name: 'Oxygen', weight: 15.9994, symbol: 'O'},
    {position: 9, name: 'Fluorine', weight: 18.9984, symbol: 'F'},
    {position: 10, name: 'Neon', weight: 20.1797, symbol: 'Ne'},
    {position: 11, name: 'Sodium', weight: 22.9897, symbol: 'Na'},
    {position: 12, name: 'Magnesium', weight: 24.305, symbol: 'Mg'},
    {position: 13, name: 'Aluminum', weight: 26.9815, symbol: 'Al'},
    {position: 14, name: 'Silicon', weight: 28.0855, symbol: 'Si'},
    {position: 15, name: 'Phosphorus', weight: 30.9738, symbol: 'P'},
    {position: 16, name: 'Sulfur', weight: 32.065, symbol: 'S'},
    {position: 17, name: 'Chlorine', weight: 35.453, symbol: 'Cl'},
    {position: 18, name: 'Argon', weight: 39.948, symbol: 'Ar'},
    {position: 19, name: 'Potassium', weight: 39.0983, symbol: 'K'},
    {position: 20, name: 'Calcium', weight: 40.078, symbol: 'Ca'},
  ];
  </code></pre>
  
  <p>Below is the Material table.</p>
  
  <pre><code>&lt;div class="example-container mat-elevation-z8"&gt;
    &lt;mat-table #table [dataSource]="dataSource"&gt;
  
      &lt;!--- Note that these columns can be defined in any order.
            The actual rendered columns are set as a property on the row definition" --&gt;
  
      &lt;!-- Position Column --&gt;
      &lt;ng-container matColumnDef="position"&gt;
        &lt;mat-header-cell *matHeaderCellDef&gt; No. &lt;/mat-header-cell&gt;
        &lt;mat-cell *matCellDef="let element"&gt; {{element.position}} &lt;/mat-cell&gt;
      &lt;/ng-container&gt;
  
      &lt;!-- Name Column --&gt;
      &lt;ng-container matColumnDef="name"&gt;
        &lt;mat-header-cell *matHeaderCellDef&gt; Name &lt;/mat-header-cell&gt;
        &lt;mat-cell *matCellDef="let element"&gt; {{element.name}} &lt;/mat-cell&gt;
      &lt;/ng-container&gt;
  
      &lt;!-- Weight Column --&gt;
      &lt;ng-container matColumnDef="weight"&gt;
        &lt;mat-header-cell *matHeaderCellDef&gt; Weight &lt;/mat-header-cell&gt;
        &lt;mat-cell *matCellDef="let element"&gt; {{element.weight}} &lt;/mat-cell&gt;
      &lt;/ng-container&gt;
  
      &lt;!-- Symbol Column --&gt;
      &lt;ng-container matColumnDef="symbol"&gt;
        &lt;mat-header-cell *matHeaderCellDef&gt; Symbol &lt;/mat-header-cell&gt;
        &lt;mat-cell *matCellDef="let element"&gt; {{element.symbol}} &lt;/mat-cell&gt;
      &lt;/ng-container&gt;
  
      &lt;mat-header-row *matHeaderRowDef="displayedColumns"&gt;&lt;/mat-header-row&gt;
      &lt;mat-row *matRowDef="let row; columns: displayedColumns;"&gt;&lt;/mat-row&gt;
    &lt;/mat-table&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>I want to generate json object of this material table.</p>