title: How disable/enable button with ionic 2?
body: <p>I have an input field and a button. It must be disable at start. When the input no blank is, the button is enable.</p>
  
  <p>I use a ngModel to take the value of the input and a function (change) to start a function each time the input is changed.</p>
  
  <p>Now I do a little if in the change function.</p>
  
  <pre><code>if(input !== ''){
  //enable the button
  }else{
  //disable the button
  }
  </code></pre>
  
  <p>Have you any idea how to achieve that?</p>
  
  <p>Thanks</p>