Cookies are small text files that are stored on a user's computer by a website. They are used to remember user preferences, login information, and other data that the website needs to function properly. In this article, we will discuss how to set cookies in JavaScript with code examples.
To set a cookie in JavaScript, you can use the document.cookie property. This property allows you to read and write cookies for the current page. To set a cookie, you need to assign a string value to the document.cookie property. The string should be in the following format:
name=value; expires=expiration_date; path=path; domain=domain; secure
nameis the name of the cookie.valueis the value of the cookie.expiresis the date when the cookie will expire. If this is not set, the cookie will be deleted when the user closes their browser.pathis the path on the server where the cookie will be available. If this is not set, the cookie will be available to all paths on the website.domainis the domain where the cookie will be available. If this is not set, the cookie will be available to all subdomains of the website.secureis an optional parameter that, when set, tells the browser to only send the cookie over secure connections (HTTPS).
Here is an example of how to set a cookie in JavaScript:
document.cookie = "username=John Doe; expires=Thu, 18 Dec 2021 12:00:00 UTC; path=/";
This sets a cookie named "username" with a value of "John Doe" that will expire on December 18, 2021. The cookie will be available to all paths on the website.
You can also set a cookie with a specific expiration date using the Date object:
var date = new Date();
date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
var expires = "expires=" + date.toUTCString();
document.cookie = "username=John Doe; " + expires + "; path=/";
This sets a cookie named "username" with a value of "John Doe" that will expire in the number of days specified by the days variable. The cookie will be available to all paths on the website.
To delete a cookie, you can set the expires value to a date in the past:
var date = new Date();
date.setTime(date.getTime() - (1000 * 60 * 60 * 24));
var expires = "expires=" + date.toUTCString();
document.cookie = "username=; " + expires + "; path=/";
This sets the expiration date of the "username" cookie to a date in the past, effectively deleting it.
It is important to note that cookies are stored on the user's computer and can be accessed by the website that set them. Be sure to handle cookies securely and never store sensitive information in them.
In conclusion, cookies are small text files that can be stored on a user's computer by a website to remember user preferences and other data. To set a cookie in JavaScript, you can use the document.cookie property and assign a string value to it in the format `name=value; expires=expiration_date; path=path; domain=domain;
In addition to setting cookies, there are a few other related topics that you may want to know more about when working with cookies in JavaScript.
First, it's important to understand how to read cookies. You can access the value of a cookie by reading the document.cookie property, which returns a string containing all the cookies for the current page, in the format name=value; name2=value2; .... You can use the split() method to convert this string into an array of key-value pairs, and then use a loop or the find() method to access the value of a specific cookie.
function getCookie(name) {
var value = "; " + document.cookie;
var parts = value.split("; " + name + "=");
if (parts.length == 2) return parts.pop().split(";").shift();
}
Another topic related to cookies is how to set and read cookies in other languages such as PHP. PHP has built-in functions for setting and reading cookies, such as setcookie() and $_COOKIE. In PHP, cookies are stored as an associative array, where the keys are the names of the cookies and the values are the cookie values.
Additionally, cookies have a size limit of 4KB, which means that you should be careful when storing large amounts of data in a cookie. If you need to store more data, you can consider using localStorage or sessionStorage instead. These are JavaScript objects that allow you to store key-value pairs in the browser, and have a larger storage limit than cookies.
When storing sensitive information, it is important to make sure that the information is encrypted before being stored in the cookie. This can be done by using a library such as crypto-js.
Finally, it's important to be aware of the browser's cookie handling policy and user's privacy. Some browsers provide options to block third-party cookies, and users can also configure their browser settings to block or clear cookies. As a developer, it's important to be aware of these settings and handle them accordingly in your code.
It is important to keep in mind that cookies are stored on the user's computer and can be accessed by the website that set them. It is important to handle cookies securely and never store sensitive information in them.
In conclusion, cookies are small text files that can be stored on a user's computer by a website to remember user preferences and other data. However, there are many other related topics such as reading cookies, setting cookies in other languages, handling large data, encryption, and user's privacy. As a developer, it's important to be aware of these topics when working with cookies.
Popular questions
- How do I set a cookie in JavaScript?
document.cookie = "name=value; expires=date; path=path; domain=domain; secure"
- How do I set a cookie with an expiration date in JavaScript?
var date = new Date();
date.setTime(date.getTime() + (exdays * 24 * 60 * 60 * 1000));
var expires = "expires=" + date.toUTCString();
document.cookie = "name=value; " + expires;
- How do I delete a cookie in JavaScript?
document.cookie = "name=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=path; domain=domain; secure"
- How do I check if a cookie exists in JavaScript?
function getCookie(name) {
var value = "; " + document.cookie;
var parts = value.split("; " + name + "=");
if (parts.length == 2) return parts.pop().split(";").shift();
}
- How can I set a cookie to only be accessible over a secure connection (HTTPS)?
document.cookie = "name=value; expires=date; path=path; domain=domain; secure"
Note that, the secure attribute indicates that the cookie should only be sent over a secure HTTPS connection from the client. If a cookie has the secure attribute, browsers will only send the cookie if the request is being sent over HTTPS, and not if it's being sent over HTTP.
Tag
Cookies.
