Each current main browser provides an API for creating a range from a mouse event, although four different code branches are required.
Here is the background:
Here is a demo: http://jsfiddle.net/timdown/krtTD/10/
And here is some code:
function getMouseEventCaretRange(evt) { var range, x = evt.clientX, y = evt.clientY; // Try the simple IE way first if (document.body.createTextRange) { range = document.body.createTextRange(); range.moveToPoint(x, y); } else if (typeof document.createRange != "undefined") { // Try Mozilla rangeOffset and rangeParent properties, // which are exactly what we want if (typeof evt.rangeParent != "undefined") { range = document.createRange(); range.setStart(evt.rangeParent, evt.rangeOffset); range.collapse(true); } // Try the standards-based way next else if (document.caretPositionFromPoint) { var pos = document.caretPositionFromPoint(x, y); range = document.createRange(); range.setStart(pos.offsetNode, pos.offset); range.collapse(true); } // Next, the WebKit way else if (document.caretRangeFromPoint) { range = document.caretRangeFromPoint(x, y); } } return range; } function selectRange(range) { if (range) { if (typeof range.select != "undefined") { range.select(); } else if (typeof window.getSelection != "undefined") { var sel = window.getSelection(); sel.removeAllRanges(); sel.addRange(range); } } } document.getElementById("editor").ondblclick = function(evt) { evt = evt || window.event; this.contentEditable = true; this.focus(); var caretRange = getMouseEventCaretRange(evt); // Set a timer to allow the selection to happen and the dust settle first window.setTimeout(function() { selectRange(caretRange); }, 10); return false; };
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