From https://once.com/writebook

app/javascript/helpers/cookie_helpers.js

@@ -0,0 +1,22 @@
+export function setCookie(name, value = "", days = 365) {
+  let expires = ""
+
+  const date = new Date()
+  date.setTime(date.getTime() + days * 24 * 60 * 60 * 1000)
+  expires = `; expires=${date.toUTCString()}`
+
+  document.cookie = `${name}=${value}${expires}; path=/`
+}
+
+export function readCookie(name) {
+  const nameEQ = `${name}=`
+  const ca = document.cookie.split(";")
+
+  for (let i = 0; i < ca.length; i++) {
+    let c = ca[i]
+    while (c.charAt(0) === " ") c = c.substring(1, c.length)
+    if (c.indexOf(nameEQ) === 0) return c.substring(nameEQ.length, c.length)
+  }
+
+  return null
+}