How to set, get and delete a cookie in Javascript

Dung Do Tien Apr 10 2020 573

I have written an application web with a login form But I want remember account when users log on and I think about cookie but I don't know how to get and set it. I need some functions to do it. (Add, get and delete)

I need any suggestions. Thanks, many

Have 1 answer(s) found.
  • S

    Sandeep Kumar Apr 11 2020

    Cookies are data, they are small items of data and store, each consisting of a name and a value. They are store on your computer. When a web server has sent a web page to a browser. In Javascript to has support cookie through document.cookie object:

    let make an example create a cookie with a path parameter, you can tell the browser what path the cookie belongs to. By default, the cookie belongs to the current page.

    document.cookie = "username=John Doe; expires=Thu, 18 Dec 2013 12:00:00 UTC; path=/";

    To manipulate easily with a cookie I make some function to read, create and delete cookie as below. 

    1. Add a Cookie

     function add_cookie(cname, cvalue, exdays) {
	var d = new Date();
	d.setTime(d.getTime() + (exdays * 24 * 60 * 60 * 1000));
	var expires = "expires=" + d.toUTCString();
	var domain = location.hostname.split('.').reverse()[1] + "." + location.hostname.split('.').reverse()[0];
	if (domain != undefined && domain.indexOf("localhost") > - 1) domain = "localhost";
	document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/;domain=." + domain;
}

    In this function, we have some domain to set some info to the cookie:

    - cname : key of the cookie

    - expires: Time cookie will be destroyed ( maybe understood delete)

    - path : url store cookie, If not specified, defaults to the current path of the current document location. In this case I set default all to "/";

    - domain: domain of website will store cookie, I have been add more dot(.) of before value to help manipulate with both main and subs domain.

     

    2. Read a cookie

    read_cookie: function (cname) {
	var name = cname + "=";
	var ca = document.cookie.split(';');
	for (var i = 0; i < ca.length; i++) {
		var c = ca[i];
		while (c.charAt(0) == ' ') {
			c = c.substring(1);
		}
		if (c.indexOf(name) == 0) {
			return c.substring(name.length, c.length);
		}
	}
	return "";
}

    As you know the cookie store by a pair of key & value, so to read a cookie you only get by key to read value.

     

    3. Delete a cookie

    To delete a cookie you only need set expire time is less than current date. Use the function of add a cookie.

     

    All Together Now

    You should aggregate them into an object for ease of use and reuse and all you need is below :

    var cookie_manager = cookie_manager || {};
cookie_manager = {
    add_cookie: function (cname, cvalue, exdays) {
        var d = new Date();
        d.setTime(d.getTime() + (exdays * 24 * 60 * 60 * 1000));
        var expires = "expires=" + d.toUTCString();
        var domain = location.hostname.split('.').reverse()[1] + "." + location.hostname.split('.').reverse()[0];
        if (domain != undefined && domain.indexOf("localhost") > - 1) domain = "localhost";
        document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/;domain=." + domain;
    },
    read_cookie: function (cname) {
        var name = cname + "=";
        var ca = document.cookie.split(';');
        for (var i = 0; i < ca.length; i++) {
            var c = ca[i];
            while (c.charAt(0) == ' ') {
                c = c.substring(1);
            }
            if (c.indexOf(name) == 0) {
                return c.substring(name.length, c.length);
            }
        }
        return "";
    }
};

    This is all custom about cookie for you. but you also using some libraries support for cookie very useful.

    Look like Jquery cookie 

    I hope this info helpful to you.

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