Add value when checkbox is clicked
<p>I have a checkbox, when it is checked, I simply want it to add 2 to a specific field called amount10.</p>

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<pre class="snippet-code-js lang-js prettyprint-override"><code>$('#checkbox2').change(function() {
  if (this.checked) {
    $("#amount10").val() + 2;
    var value = parseInt($(this).val());
    deliverySliderValue = value;
  }
});</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"&gt;&lt;/script&gt;</code></pre>
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