How to get selected text/caret position of an input that doesn't have focus?

Question

Is it possible to (reliably) get the selected text/caret position in a input text box if that field doesn't have focus?

If not, what's the best way to get and retain this data?

Basically, when a user clicks a button I want to insert some text at the caret position. However, as soon as the user clicks that button, the field loses focus and I lose the caret position.

Solution 1

The following script will hold the caret position and then a button click will insert text at the stored position:

Javascript:

<script type="text/javascript">
//Gets the position of the cursor
function getCaret(el) { 
  if (el.selectionStart) { 
    return el.selectionStart; 
  } else if (document.selection) { 
    el.focus(); 

    var r = document.selection.createRange(); 
    if (r == null) { 
      return 0; 
    } 

    var re = el.createTextRange(), 
        rc = re.duplicate(); 
    re.moveToBookmark(r.getBookmark()); 
    rc.setEndPoint('EndToStart', re); 

    return rc.text.length; 
  }  
  return 0; 
}

function InsertText() {
    var textarea = document.getElementById('txtArea');
    var currentPos = getCaret(textarea);
    var strLeft = textarea.value.substring(0,currentPos);
    var strMiddle = "-- Hello World --";
    var strRight = textarea.value.substring(currentPos,textarea.value.length);
    textarea.value = strLeft + strMiddle + strRight;
}
</script>

HTML:

<textarea id="txtArea" >Lorem ipsum dolor sit amet, consectetur adipiscing elit.</textarea>
<button onclick="InsertText();">Insert Text</button>

The script can be modified if you want to hold the caret position in a variable onblur.

Solution 2

Use the following 2 functions to save and restore text selection.

function saveSelection() {
    if (window.getSelection) {
        sel = window.getSelection();
        if (sel.getRangeAt && sel.rangeCount) {
            return sel.getRangeAt(0);
        }
    } else if (document.selection && document.selection.createRange) {
        return document.selection.createRange();
    }
    return null;
}

function restoreSelection(range) {
    if (range) {
        if (window.getSelection) {
            sel = window.getSelection();
            sel.removeAllRanges();
            sel.addRange(range);
        } else if (document.selection && range.select) {
            range.select();
        }
    }
}

Check Working example at http://jsfiddle.net/LhQda/

Type something in the TEXTAREA, then click outside the TEXTAERA to lose the selection, then click on the focus button to restore selection and focus again.

Comments

[mpen]

You realize your code does absolutely nothing, and doesn't work in IE right? saveSelection returns the selection, which you haven't stored in a variable or anything, and restoreSelection takes a range as a parameter into which you have passed nothing. Your example works in FF because FF doesn't lose the caret position by default. IE (and perhaps other browsers) do.

[Hussein]

I didn't realize that. In your question you stated you wanted to get selected text/caret position of an input that doesn't have focus?. The code gives you both focus and selected text.

[mpen]

took me awhile to get it working, but it does seem to workin FF and IE jsfiddle.net/EDWw8

[mpen]

i don't really want/need to focus the element, that's easy to do, i just need the positions, which are also easy to get. the problem is when the element is out of focus, the positions are not retrievable in some browsers. i think though, that simply focusing the field before trying to get the positions might fix the problem, but i don't know if that's a reliable fix. I don't see how your window.getSelection would be useful if there are multiple inputs on the page, assuming it grabs what...the last selected text?

[NakedBrunch]

Works in Chrome9 and IE9 too. Good job. Since you haven't accepted the answer, is there something else that you're trying to do?

[mpen]

Let's not get impatient. Alex's solution is perfectly viable too, and it looks to be more robust. I'll accept an answer once I implement it and decide which one actually works better for me.

[metric152]

This was a big help. I needed to patch a problem in Rangyinputs where IE9 wasn't picking up the cursor position. Now I need to figure out how to submit a patch to them.

[Shanimal]

this answer still hasn't been accepted. it's been two years. what gives?

[BenG]

if el.selectionStart === 0, which entirely valid, this code will fail