title: I do not understand the math operators used here
body: <p>I don't understand the +=+ and ++ used in calculations in this code. If I use += and single plus sign instead the calculations do not work.</p>
  <pre><code>               document.getElementById(&quot;addbtn&quot;).addEventListener(&quot;click&quot;,addnumbers);
          }
            function addnumbers() {
           var answer = &quot;&quot;; 
             answer +=+
              document.getElementById(&quot;inputOne&quot;).value + +
              document.getElementById(&quot;inputTwo&quot;).value
   
              alert(answer)
           };
  </code></pre>