Cookies

1 min read | JavaScript Tutorial

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document.cookie

Cookies are small pieces of data stored in the browser. Access them via document.cookie as a semicolon-separated string.

document.cookie = "username=Alice";
document.cookie = "theme=dark";

console.log(document.cookie);

Setting Cookies with Options

Set path, expiration, and Secure/HttpOnly flags. Use max-age or expires for persistence.

function setCookie(name, value, days) {
  const date = new Date();
  date.setTime(date.getTime() + days * 86400000);
  document.cookie = name + "=" + value + ";expires=" + date.toUTCString() + ";path=/";
}

setCookie("preferences", "dark_mode", 7);
console.log(document.cookie);

Reading & Deleting Cookies

Parse document.cookie to read specific values. Delete by setting a past expiration date.

function getCookie(name) {
  const cookies = document.cookie.split("; ");
  for (let c of cookies) {
    const [key, value] = c.split("=");
    if (key === name) return value;
  }
  return null;
}

function deleteCookie(name) {
  document.cookie = name + "=;expires=Thu, 01 Jan 1970 00:00:00 UTC;path=/";
}

console.log(getCookie("username"));
deleteCookie("username");
console.log(getCookie("username"));

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