title: Conditionally add custom button in ng2-smart-table
body: <p>In ng2-smart-table, I want a button 'Start' or 'End' which I am showing conditionally. How can I do this?
  I am having a condition If that's true, then I want to show 'Start' button and if it is false, then I want to show 'End' button. Also, I need to perform something if a user clicks these buttons.</p>
  
  <pre><code>tableSettings = {
  actions: false,
  columns: {
    code: {
      title: 'Code'
    },
    first_name: {
      title: 'First Name'
    },
    last_name: {
      title: 'Last Name'
    },
    email_id: {
      title: 'Email'
    },
    start_time: {
      title: 'Start Time',
      type: 'date',
      valuePrepareFunction: (date) =&gt; { 
        return this.renderDateTime(date); 
      }
    },
    end_time: {
      title: 'End Time',
      type: 'date',
      valuePrepareFunction: (date) =&gt; {
        return this.renderDateTime(date); 
      }
    },
    start: {
      title: 'Start/End',
      type: 'html',
      valuePrepareFunction: (cell, row) =&gt; {
        return `&lt;button *ng-If="renderButton(row) === 'Start'" (click)="startTest()"&gt;Start&lt;/button&gt;`; 
      }
    }
  }
  </code></pre>
  
  <p>};</p>