Getting selected text with Rails and Turbolinks

June 6, 2013

I have to start by confessing that I don’t know what it is about Turbolinks that caused the issue I was having. I’m only edu-guessing that Turbolinks is the cause.

So…I needed to know the text that the user had selected with their cursor. This would be used to create context for the comment they wanted to make on the text. I started by using a popular method I found on Stack Overflow.

function getSelectionText() {
  if (window.getSelection) {
    return window.getSelection().toString();
  } else if (document.selection && document.selection.type != "Control") {
    return document.selection.createRange().text;
  }
}

This worked fine in a static proof of concept. It also initially worked in my Rails project. By initially I mean after a browser refresh. As soon as I navigated to other pages and retested the function fell through and returned nothing. The rest of my javascript is fine. I am displaying a positioned button after text is selected and once clicked, the button performs an action with the selected text. This all works as expected.

I don’t know enough about the DOM or getSelection method to figure it out on my own. I set Google on it, which turned up a different function from the rest.

function GetSelectedText() {
  var selectedText = (
    window.getSelection
    ?
      window.getSelection()
    :
      document.getSelection
      ?
        document.getSelection()
      :
        document.selection.createRange().text
  );
  if (!selectedText || selectedText=="") {
    if(document.activeElement.selectionStart) {
      selectedText = document.activeElement.value.substring(
        document.activeElement.selectionStart
        . document.activeElement.selectionEnd);
    }
  }
  return selectedText;
}

That is now working. Or at least it fixes my previous bug. It’s the nested if where selectedText is blank that solves it. I don’t like the if else in the selectedText initiation so I’m using the original function is start with.