JS Cookbook - Get Highlighted Text

Coding

1. function getSelection() {
      var text = "";
      if (window.getSelection) {
          text = window.getSelection().toString();
      }
      return text;
   }
   
   document.onselectionchange = function() {
     document.getElementById("sel").value = getSelectionText();
   };

Kaynak

1. Stackoverflow - link
2. Caniuse getSelection - link