Saving and Restoring caret position for contentEditable div
Solution 1:
back to 2016 :)
After I came across solutions here and they did not suit me, because my DOM was replaced completely after each typing. I've done more research and come with a simple solution that saves the cursor by character's position that works perfect for me.
The idea is very simple.
- find the length of characters before caret and save it.
- change the DOM.
- using
TreeWalker
to walk just ontext nodes
ofcontext node
and counting characters until we got the righttext node
and the position inside it
Two edge case:
-
content removed completely so there is no
text node
:
so: move the cursor to the start of the context node -
there is less content than the
index
pointed on :
so: move the cursor to the end of the last node
function saveCaretPosition(context){
var selection = window.getSelection();
var range = selection.getRangeAt(0);
range.setStart( context, 0 );
var len = range.toString().length;
return function restore(){
var pos = getTextNodeAtPosition(context, len);
selection.removeAllRanges();
var range = new Range();
range.setStart(pos.node ,pos.position);
selection.addRange(range);
}
}
function getTextNodeAtPosition(root, index){
const NODE_TYPE = NodeFilter.SHOW_TEXT;
var treeWalker = document.createTreeWalker(root, NODE_TYPE, function next(elem) {
if(index > elem.textContent.length){
index -= elem.textContent.length;
return NodeFilter.FILTER_REJECT
}
return NodeFilter.FILTER_ACCEPT;
});
var c = treeWalker.nextNode();
return {
node: c? c: root,
position: index
};
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.5.1/prism.min.js"></script>
<link href="https://rawgit.com/PrismJS/prism/gh-pages/themes/prism.css" rel="stylesheet"/>
<style>
*{
outline: none
}
</style>
<h3>Edit the CSS Snippet </H3>
<pre>
<code class="language-css" contenteditable=true >p { color: red }</code>
</pre>
<script >
var code = document.getElementsByTagName('code')[0];
code.addEventListener('input',function () {
var restore = saveCaretPosition(this);
Prism.highlightElement(this);
restore();
})
</script>
Solution 2:
I know this is an ancient thread but I thought I would provide an alternative non-library solution
http://jsfiddle.net/6jbwet9q/9/
Tested in chrome, FF, and IE10+ Allows you to change, delete and restore html while retaining caret position/selection.
HTML
<div id=bE contenteditable=true></div>
JS
function saveRangePosition()
{
var range=window.getSelection().getRangeAt(0);
var sC=range.startContainer,eC=range.endContainer;
A=[];while(sC!==bE){A.push(getNodeIndex(sC));sC=sC.parentNode}
B=[];while(eC!==bE){B.push(getNodeIndex(eC));eC=eC.parentNode}
return {"sC":A,"sO":range.startOffset,"eC":B,"eO":range.endOffset};
}
function restoreRangePosition(rp)
{
bE.focus();
var sel=window.getSelection(),range=sel.getRangeAt(0);
var x,C,sC=bE,eC=bE;
C=rp.sC;x=C.length;while(x--)sC=sC.childNodes[C[x]];
C=rp.eC;x=C.length;while(x--)eC=eC.childNodes[C[x]];
range.setStart(sC,rp.sO);
range.setEnd(eC,rp.eO);
sel.removeAllRanges();
sel.addRange(range)
}
function getNodeIndex(n){var i=0;while(n=n.previousSibling)i++;return i}