only-changed-jest-watch-plugin/example/node_modules/jest-watcher/build/lib/scroll_list.js

Jest watch plugin for running either only the modified test (for TDD), or tests of dependant modules

/**
 * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 *
 */

'use strict';

Object.defineProperty(exports, '__esModule', {
  value: true
});
exports.default = scroll;
function scroll(size, _ref) {
  let offset = _ref.offset,
    max = _ref.max;

  let start = 0;
  let index = Math.min(offset, size);

  const halfScreen = max / 2;

  if (index <= halfScreen) {
    start = 0;
  } else {
    if (size >= max) {
      start = Math.min(index - halfScreen - 1, size - max);
    }
    index = Math.min(index - start, size);
  }

  return {
    end: Math.min(size, start + max),
    index: index,
    start: start
  };
}