tootlab-mastodon/app/javascript/core/settings.js

//  This file will be loaded on settings pages, regardless of theme.

import 'packs/public-path';
import Rails from '@rails/ujs';

Rails.delegate(document, '#edit_profile input[type=file]', 'change', ({ target }) => {
  const avatar = document.getElementById(target.id + '-preview');
  const [file] = target.files || [];
  const url = file ? URL.createObjectURL(file) : avatar.dataset.originalSrc;

  avatar.src = url;
});

Rails.delegate(document, '.input-copy input', 'click', ({ target }) => {
  target.focus();
  target.select();
  target.setSelectionRange(0, target.value.length);
});

Rails.delegate(document, '.input-copy button', 'click', ({ target }) => {
  const input = target.parentNode.querySelector('.input-copy__wrapper input');

  const oldReadOnly = input.readonly;

  input.readonly = false;
  input.focus();
  input.select();
  input.setSelectionRange(0, input.value.length);

  try {
    if (document.execCommand('copy')) {
      input.blur();
      target.parentNode.classList.add('copied');

      setTimeout(() => {
        target.parentNode.classList.remove('copied');
      }, 700);
    }
  } catch (err) {
    console.error(err);
  }

  input.readonly = oldReadOnly;
});