selection on editable div doesn't work if an Enter is typed

Question

I have an editable div and multiple blocks of texts between a starting three backticks and ending three backticks markers
Let's say the cursor is anywhere between the markers
Clicking on a button I need to select entire current block

This code works until I type Enter anywhere inside the current block
Also - I believe there is a shorter version of the code

function get_left(){
let s = window.getSelection();
let range = s.getRangeAt(0);
let so = range.startOffset;
let textNode = range.startContainer;
let textContent = textNode.textContent;
let startPosition = Math.max(so - 4, 0);
let a = textContent.substring(startPosition, so);
return a;
}


function go_left(){
    let par = document.getElementById("cstory");
  let s = window.getSelection();
  let range = document.createRange();
  let cp = window.getSelection().getRangeAt(0).startOffset;
  let textNode = par.firstChild;
    range.setStart(textNode, cp - 1);
    range.setEnd(textNode, cp - 1);
    s.removeAllRanges();
    s.addRange(range);
}

$('button').on('click', async function(){
    while(get_left() !== "```\n"){go_left();}
    let s = window.getSelection();
    let range = s.getRangeAt(0);
    let story = document.getElementById("cstory").innerText;
    let nextXIndex = story.indexOf("\n```", range.endOffset);
    if(nextXIndex !== -1){
        range.setEnd(range.endContainer, nextXIndex);
        s.removeAllRanges();
        s.addRange(range);
    }
});

.cstory{white-space:pre-wrap;}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class='cstory' id='cstory' contenteditable>
lorem sea
```
lorem ipsum
dolor sit
sky
```
lorem sky

```
lorem ipsum
dolor sit
sky
```
dolor sit
</div>
<br>
<button>CLICK</button>

Answer 1

no additional libraries are needed. plain JS solution here, preventing divs creation and replacing the double quotes so it can work smoothly, as the requirement is to select text which is between backticks, double quotes were disrupting the format and selections were not working

document.querySelector('div[contenteditable]').addEventListener('keydown', function(e) {
  // creating a new selection element
  let sltcn = window.getSelection()
  // identifying the current position of the cursor within the text
  let range = sltcn.getRangeAt(0)
  // saveing the current cursor position in a variable
  let position = range.startOffset

  if (event.key === 'Enter') {
    document.execCommand('insertLineBreak');
    
    // getting the content of the inner HTML of the 'cstory' element and removing any quotation marks
    let content = document.getElementById("cstory").innerHTML;
    content = content.replace(/"/g, "");
    // updating the content without quotation marks
    document.getElementById("cstory").innerHTML = content;
    
     // checking if the cursor is at the end of the text
    if (position === range.endOffset) {
      // creating a new range at the start of the next paragraph
      let newRange = document.createRange();
      newRange.setStart(document.getElementById("cstory").childNodes[0], position + 1);
      newRange.collapse(true);
      
      sltcn.removeAllRanges();
      sltcn.addRange(newRange);
    } else {
      // cursor is in the middle of the line, moving it to the end
      range.setStart(document.getElementById("cstory").childNodes[0], position + 1);
      sltcn.removeAllRanges();
      sltcn.addRange(range);
    }
    
    event.preventDefault()
  }
});

function clsl() {
  // getting the 'cstory' element
  let cstory = document.getElementById("cstory");

  // Getting the cursor position within the div
  let crpos = window.getSelection().getRangeAt(0).startOffset;
  
  // getting the text content
  let cont = cstory.textContent;

  // getting the position of the last 3 backticks
  let firstticks = cont.lastIndexOf("```", crpos-1);

  // getting the position of the first 3 backticks
  let lastticks = cont.indexOf("```", crpos);

  // If both starting and ending backticks are found, selecting the text between them
  if (firstticks !== -1 && lastticks !== -1){
    // Setting the selection range to start after the first backtick and end before the last backtick
    let sltcn = window.getSelection();
    let range = document.createRange();
    // Setting the start and end of the range to include the text between the backticks
    range.setStart(cstory.childNodes[0], firstticks+4);
    range.setEnd(cstory.childNodes[0], lastticks);
    sltcn.removeAllRanges();
    sltcn.addRange(range);

  }
}

.cstory{white-space:pre-wrap;}

<div class='cstory' id='cstory' contenteditable>
lorem sea
```
lorem ipsum
dolor sit
sky
```
lorem sky

```
lorem ipsum
dolor sit
sky
```
dolor sit
</div>
<br>
<button onclick="clsl()">CLICK</button>