chromium/third_party/google-closure-library/closure/goog/demos/dom_selection.html

<!DOCTYPE html>
<html>
<!--
Copyright The Closure Library Authors. All Rights Reserved.

Use of this source code is governed by the Apache License, Version 2.0.
See the COPYING file for details.
-->
<head>
<title></title>
<style>

label {
  display: block;
}

</style>
<script src="../base.js"></script>
<script>
goog.require('goog.dom');
goog.require('goog.dom.selection');
</script>
</head>
<body>

<script>

var $ = goog.dom.getElement;

var isSyncing = false;

function update(i) {
  isSyncing = true;
  var selectionStart = $('selectionStart' + i).value;
  var selectionEnd = $('selectionEnd' + i).value;
  var selectionText = $('selectionText' + i).value;
  var textField = $('textField' + i);
  textField.focus();

  if (!isNaN(selectionStart)) {
    goog.dom.selection.setStart(textField, selectionStart);
  }

  if (!isNaN(selectionEnd)) {
    goog.dom.selection.setEnd(textField, selectionEnd);
  }

  selection.setText(textField, selectionText);
  isSyncing = false;
  sync(i);
}

function sync(i) {
  isSyncing = true;
  var textField = $('textField' + i);
  $('selectionStart' + i).value = goog.dom.selection.getStart(textField);
  $('selectionEnd' + i).value = goog.dom.selection.getEnd(textField);
  $('selectionText' + i).value = goog.dom.selection.getText(textField);
  isSyncing = false;
}

</script>

<label>selectionStart <input type=text id=selectionStart1></label>
<label>selectionEnd <input type=text id=selectionEnd1></label>
<label>selectionText <input type=text id=selectionText1></label>
<button onclick="update(1)">Update Textarea</button><br>

<textarea id=textField1 onkeydown="sync(1)" onkeyup="sync(1)"></textarea>


<label>selectionStart <input type=text id=selectionStart2></label>
<label>selectionEnd <input type=text id=selectionEnd2></label>
<label>selectionText <input type=text id=selectionText2></label>
<button onclick="update(2)">Update Input</button><br>
<input type=text id=textField2 onkeydown="sync(2)" onkeyup="sync(2)">

<script>

window.onload = function() {
  sync(1);
  sync(2);
};

</script>

</body>
</html>