How to manage Cookies in the Browser via Javascript?

All

• Read the cookies. The cookies are in a string separated with a ;

console.log("All the cookies:");
console.log(document.cookie);

Filter

• Only the cookie that starts with an underscore

console.log("All the cookies:");
console.log(document.cookie.split("; ").filter( (item) => item.trim().startsWith('_') ));

by name

There is no function in the Javascript Web API to get a cookie by name.

We need to parse the value of document.cookie. This is a string of all cookies in a key pair format separated by a ;

• Setting a cookie

cookie_key = "name";
document.cookie = cookie_key+"=nico";

• Regular expression method. Because the key value is saved in variable, we cannot create a regular expression pattern as a string and need to use a regexp constructor

regexp = new RegExp("(?:(?:^|.*;\\s*)"+cookie_key+"\\s*\\=\\s*([^;]*).*$)|^.*$");
var cookieValue = document.cookie.replace(regexp, "$1");
console.log("Regular expression    : The value of the cookie with the name key is ("+cookieValue+")");

• Functional Programming method

var cookieValue = document.cookie
    .split(";")
    .filter( (item) => item.trim().startsWith(cookie_key) )[0]
    .split("=")[1];
console.log("Functional Programming: The value of the cookie with the name key is ("+cookieValue+")");

• Result