@findify/react-components/lib/helpers/getBreakpoint.js

Findify react UI components

var isFunction = function isFunction(check) {
  return check && {}.toString.call(check) === '[object Function]';
};

export default (function (breakpoints) {
  var width = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : window.innerWidth;
  if (!breakpoints) return undefined;
  if (isFunction(breakpoints)) return breakpoints(width);
  var points = Object.keys(breakpoints);
  return points.sort(function (a, b) {
    return parseInt(a, 10) - parseInt(b, 10);
  }).filter(function (point) {
    return Number(point) <= width;
  }).pop() || points[0];
});