@researchgate/react-intersection-list/lib/js/utils.js

React List Component using the Intersection Observer API

"use strict";

exports.__esModule = true;
exports.computeRootMargin = computeRootMargin;
exports.getItemCount = getItemCount;
exports.computeSize = computeSize;

var _warning = _interopRequireDefault(require("warning"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { "default": obj }; }

function computeRootMargin(_ref) {
  var threshold = _ref.threshold,
      axis = _ref.axis;
  var margins = [threshold];
  var unit = threshold.match(/^-?\d*\.?\d+(px|%)$/) || [''];
  var value = "0" + unit.pop();

  if (axis === 'y') {
    margins.push(value);
  } else {
    margins.unshift(value);
  }

  return margins.join(' ');
}

function getItemCount(_ref2, warnIfConflict) {
  var itemCount = _ref2.itemCount,
      items = _ref2.items;
  var hasItemCount = typeof itemCount !== 'undefined';
  var hasItems = typeof items !== 'undefined';
  var defaultValue = 0;

  if (warnIfConflict) {
    (0, _warning["default"])(!(hasItemCount && hasItems), 'ReactIntersectionList: cannot use itemCount and items props at the same time, choose one to determine the number of items to render.');
  }

  if (hasItemCount) {
    return itemCount;
  }

  return hasItems ? items.length || items.size || defaultValue : defaultValue;
}

function computeSize(pageSize, itemCount) {
  return Math.max(0, Math.min(pageSize, itemCount));
}