const parseCookie = str =>
str
.split(';')
.map(v => v.split('='))
.reduce((acc, v) => {
acc[decodeURIComponent(v[0].trim())] = decodeURIComponent(v[1].trim());
return acc;
}, {});
// cookie in browser: `pkg=math; equation=E%3Dmc%5E2`
parseCookie(document.cookie);
//console: { pkg: 'math', equation: 'E=mc^2' }