Question 160391 in Javascript Question posted in
A very good W3school tutorial can be found here.

Can Javascript regex replace everything except what contains a specific word?

I guess it’s trivial but I’m struggling with the following situation:

String (HTML delievered as text):

text<br>text<br><ul><li>text</li></ul><br>

Now I need to replace every text<br> with <div>text</div>
except if text is inside <li>/<ul>.

.replace(/(.*?)<br>/g, '<div>$1</div>')

This works fine but how to prevent <ul><li>text</li></ul><br> from beeing replaced?

Tags:

3

Answers


  1. Chosen as BEST ANSWER
    0

    This was my attempt before asking for a (shorter) regex solution:

    const dFrag = document.createDocumentFragment();
str.textContent.split('<br>').forEach(substr => {
  const div = document.createElement('div');
  let ul;
  if (!substr) {
    substr = '<br>';
  }
  div.innerHTML = substr;
  ul = div.querySelector('ul');
  if (ul) {
    dFrag.appendChild(ul);
  } else {
    dFrag.appendChild(div);
  }
});
str.innerHTML = '';
str.appendChild(dFrag);

    Cause I'm splitting the string at <br> the tag itself gets lost. So if no substr exists (empty line) I write <br> as substr and empty lines are getting parsed as <div><br></div>. But I was not able to catch an empty line after <ul>:

    <ul>
  <li>text</li>
</ul>
<br>
text<br>

    In that case substr exists and the empty line gets lost.


  2. 0

    If you prefer using regex use /(?!<li.?>)(?!</li>)(?!<ul.?>)(?!</ul>)(.?)
    /g*

    const html = 'text<br>text<br><ul><li>text</li></ul><br>';
const regex = /(?!<li.*?>)(?!</li>)(?!<ul.*?>)(?!</ul>)(.*?)<br>/g;
const replacedHtml = html.replace(regex, '<div>$1</div>');
console.log(replacedHtml);

    But it would be better if you switch to HTML parser to easily navigate and modify the structure of the HTML content

    Login or Signup to reply.
  3. 0

    "You can’t parse [HTML] with regex. […] Have you tried using an [HT]ML parser instead?"™

    (a terser version can be found in the snippet below)

    function replaceTextBrWithDiv(html) {
  // Create an element that acts as a parser
  const parser = document.createElement('div');
  parser.innerHTML = html;

  // Modify an array-like when iterating over it may cause some issues.
  // Copy it first.
  const childNodes = [...parser.childNodes];

  // Index-based iterating
  for (let index = 0; index < childNodes.length; index++) {
    const node = childNodes[index];
    const nextNode = childNodes[index + 1];

    if (node instanceof Text && nextNode instanceof HTMLBRElement) {
      const div = document.createElement('div');

      // Remove text node from parser and append it to div
      div.appendChild(node);
      nextNode.replaceWith(div);

      // Skip next node (i.e. <br>)
      index++;
    }
  }

  return parser.innerHTML;
}

    Try it:

    console.config({ maximize: true });

function replaceTextBrWithDiv(html) {
  const parser = document.createElement('div');
  parser.innerHTML = html;

  parser.childNodes.forEach((node, index, nodes) => {
    const nextNode = nodes[index + 1];
    
    if (node instanceof Text && nextNode instanceof HTMLBRElement) {
      const div = document.createElement('div');
      div.appendChild(node);
      nextNode.replaceWith(div);
    }
  });
  
  return parser.innerHTML;
}

const content = 'text<br>text<br><ul><li>text</li></ul><br>';

console.log(replaceTextBrWithDiv(content));
    <script src="https://gh-canon.github.io/stack-snippet-console/console.min.js"></script>
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