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' }
Браузер
JavaScript