Bookmarklet for selecting code snippets on StackExchange in 2021

Question

The following code will add to each code block on https://codereview.stackexchange.com/ or https://stackoverflow.com/ a 'Select Code' button that will select the code belonging to that block.

This was originally written in 2013, I adjusted it to the new CSS and exchanged var with let, otherwise I think it looks fine. However JS has changed a lot, so I am submitting it again.

The original code was reviewed here 7 years ago.

In order to use this, visit http://codereviewcommunity.github.io/CodeReviewBookmarklet/

javascript: $('pre.s-code-block').not('button + *').each(function createButton() {
 /* Thank you http://stackoverflow.com/a/2838358/7602 */
 function selectCode(el, win) {
 win = win || window;
 let doc = win.document,
 sel, range;
 if (win.getSelection && doc.createRange) {
 sel = win.getSelection();
 range = doc.createRange();
 range.selectNodeContents(el);
 sel.removeAllRanges();
 sel.addRange(range);
 } else if (doc.body.createTextRange) {
 range = doc.body.createTextRange();
 range.moveToElementText(el);
 range.select();
 }
 }
 let buttonText = 'Select Code',
 length = buttonText.length,
 codeBlock = this,
 $link = $('<button type=\'button\'>' + buttonText + '</button>').click(function buttonListener() {
 console.log($(codeBlock).text().substring(length));
 selectCode(codeBlock);
 });
 $(codeBlock).before($link);
});
/* Cross browser bookmarklet sorcery */
void(0);