Adds handling of ?dev=1 in URL for testing

Author: alderg

tools/mermaid.html

@@ -10,7 +10,8 @@
 function create()
 {
   var value = document.getElementById('textarea').value;
-  var link = 'https://www.draw.io/?create=' + encodeURIComponent(JSON.stringify({type: 'mermaid', data: value}));
+  var prefix = (window.location.search == '?dev=1') ? 'https://test.draw.io/?dev=1&' : 'https://www.draw.io/?';
+  var link = prefix + 'create=' + encodeURIComponent(JSON.stringify({type: 'mermaid', data: value}));
   document.getElementById('link').innerHTML = '<a href="' + link + '" target="_blank">Link</a>';
   window.open(link);
 };