"Failed to execute 'addRange' on 'Selection': parameter 1 is not of type 'Range'

Question

I want to mirror the text selection in a contenteditable div in one browser in another browser. The simplified and relevant section of the code is:

In the source browser:

function someFunc() {
  if (window.getSelection().isCollapsed)
       return;
  var range = window.getSelection().getRangeAt(0);
  
  //Send range over websockets to another browser
  sendToAnotherBrowser(...) //Send range

}

In the remote browser, I execute the following code:

 var sel = window.getSelection();
 sel.addRange(range);  //Where range is the range transmitted over webSockets

I get the following error:

 "Failed to execute 'addRange' on 'Selection': parameter 1 is not of type 'Range'

QUESTION: How to transmit the "Range" object over websockets? It is not a JSON object to be stringified and sent. Can I serialize it somehow, change it to base64 and then reverse the process on the receiving end?

Answer 1

You can't serialize the object itself, buy you can create an object that contains the data of the Range object, send it to the socket and build a new Range object from there.

const sendRange = range => {
  const {
    startContainer,
    endContainer,
    startOffset, 
    endOffset, 
    collapsed
  } = range;
  const package = JSON.stringify({
    startNodeId: startContainer.id,
    endNodeId: endContainer.id,
    startOffset, 
    endOffset
    collapsed
  });
  sendToAnotherBrowser(package);
}

const range = window.getSelection().getRangeAt(0);
sendRange(range);

And receive it somewhere else where you build a new object.

const buildRange = package => {
  const { 
    startNodeId,
    endNodeId,
    startOffset, 
    endOffset, 
    collapsed 
  } = JSON.parse(package);
  const selection = window.getSelection();
  const range = document.createRange();
  const startNode = document.getElementById(startNodeId);
  const endNode = document.getElementById(endNodeId);
  range.setStart(startNode, startOffset);
  range.setEnd(endNode, endOffset);
  if (collapsed) {
    range.collapse();
  }
  selection.addRange(range);
}