Detect size Bootstrap grid.js

// Bootstrap version 4
function detectSizeBootstrapGrid() {
    let envs = ['xs', 'sm', 'md', 'lg', 'xl'];

    // Create element to get name size
    let el = document.createElement('div');
    document.body.appendChild(el);

    let size = envs.shift();

    for (let env of envs.reverse()) {
    
      el.classList.add('d-' + env + '-none');

      // Added display none to not displaying in your application
      if (window.getComputedStyle(el).display === 'none') {
        // Redefine var size to grid size of bootstrap
        size = env;
        break;
      }
    }

    document.body.removeChild(el);
    return size;
  }