parseCookie

Parses an HTTP Cookie header string, returning an object of all cookie name-value pairs.

• Use String.prototype.split(';') to separate key-value pairs from each other.
• Use Array.prototype.map() and String.prototype.split('=') to separate keys from values in each pair.
• Use Array.prototype.reduce() and decodeURIComponent() to create an object with all key-value pairs.

const parseCookie = str =>
  str
    .split(';')
    .map(v => v.split('='))
    .reduce((acc, v) => {
      acc[decodeURIComponent(v[0].trim())] = decodeURIComponent(v[1].trim());
      return acc;
    }, {});

parseCookie('foo=bar; equation=E%3Dmc%5E2');
// { foo: 'bar', equation: 'E=mc^2' }