Parse document.cookie into object

parsecookie.js

document.cookie.split(';').map(function(c) {
  return c.trim().split('=').map(decodeURIComponent);
}).reduce(function(a, b) {
  try {
    a[b[0]] = JSON.parse(b[1]);
  } catch (e) {
    a[b[0]] = b[1];
  }
  return a;
}, {});

"What ain't tested, ain't working"

The only implementation in the comments that passes most of the tests from jshttp/cookie is the one from @kapouer: https://gist.github.com/rendro/525bbbf85e84fa9042c2?permalink_comment_id=3084097#gistcomment-3084097

So I've fixed the remaining failing tests and refactored a bit the code.

Here the result:

function decode(str: string) {
  try {
    return decodeURIComponent(str);
  } catch {
    return str;
  }
}

/**
 * Parses a `Cookie` HTTP header value or `document.cookie` into an object.
 *
 * Implementation adapted from https://gist.github.com/rendro/525bbbf85e84fa9042c2?permalink_comment_id=3084097#gistcomment-3084097
 */
export function parseCookie(cookies: string) {
  const obj = Object.create(null) as Record<string, string | undefined>;

  const list = cookies.split(';');

  for (const cookie of list) {
    if (cookie === '') continue;

    const eq = cookie.indexOf('=');

    const key = (eq > 0 ? cookie.slice(0, eq) : cookie).trim();
    const value = eq > 0 ? decode(cookie.slice(eq + 1).trim()) : undefined;

    if (!(key in obj)) {
      obj[key] = value;
    }
  }

  return obj;
}

You can retrieve this implementation + all the tests and benchs in this gist: https://gist.github.com/tkrotoff/a1f83070067300174fbe9f35d0075dd3