WordPress Media Library with pre-selected items

upload.js

/**
 * Utilize WordPress' media library. Easy select/upload files for your plugin/theme admin page.
 * It uses build-in jQuery 1.4.1
 * Tested with WordPress 5.2.4
 */

$('.my-upload-button').click(function(e) {
  e.preventDefault();

  // setup our media library frame
  let frame = wp.media({
    title: 'Upload your pictures',
    multiple: true, // allows user to select multiple files at once
    library: {
      type: 'image', // if you need only images
    },
  });

  // if you have IDs of previously selected files you can set them checked
  frame.on('open', function() {
    let selection = frame.state().get('selection');
    let ids = [13, 14, 56]; // array of IDs of previously selected files. You're gonna build it dynamically
    ids.forEach(function(id) {
      let attachment = wp.media.attachment(id);
      selection.add(attachment ? [attachment] : []);
    }); // would be probably a good idea to check if it is indeed a non-empty array
  });

  // get the URLs of the selected items
  frame.on('select', function() {
    let selection = frame.state().get('selection');
    let images = [];
    selection.models.map(function(image) {
      images.push({
        id: image.attributes.id,
        url: image.attributes.url,
      });
    });
    console.log(images);
  });

  // open wp media library frame
  frame.open();

});