Simple function to read a named cookie from the document.cookie string

read-cookie.js

/**
 * Read a cookie value by its name
 * @param { String } name - cookie identifier
 * @returns { String } the cookie found or an empty string
 */
export default function readCookie(name) {
  const cookie = document.cookie;
  const patternRegex = new RegExp(`${ name }=(?:["|'])?([^"';]+)(?:\\1)?`, 'gi');
  const match = patternRegex.exec(cookie);
    
  return match && match.length > 1 ? match[1] : '';
}

Usage

Test string:

django_language=de; csrftoken=SuktrIZlUwvk4E0LoKyIHVraBlG0UiLn; _ga=GA1.1.409523848.1476253469; __atuvc=32%7C46%2C0%7C47%2C0%7C48%2C33%7C49%2C143%7C50; ajs_user_id=null; ajs_group_id=null; ajs_anonymous_id=%222646bc13-49e5-43ae-a204-7641fd6027ca%22; intercom-id-pcdclcus=c489b10f-34c4-4fc2-8d9c-fa190b3ab937; __atuvs=584e8c24077fa261047; created_snowflakes="e12e3901-c966-4088-abdb-7415e232dfad\054c08669a1-e11e-4f75-8d78-a45001f6fe97"

const lang = readCookie('django_language') // 'de'
const userId = readCookie('ajs_user_id') // 'null'
const createdSnowflakes = readCookie('created_snowflakes') // 'e12e3901-c966-4088-abdb-7415e232dfad\054c08669a1-e11e-4f75-8d78-a45001f6fe97'