Clearing all cookies with JavaScript

function deleteAllCookies() {
    var cookies = document.cookie.split(";");

    for (var i = 0; i < cookies.length; i++) {
        var cookie = cookies[i];
        var eqPos = cookie.indexOf("=");
        var name = eqPos > -1 ? cookie.substr(0, eqPos) : cookie;
        document.cookie = name + "=;expires=Thu, 01 Jan 1970 00:00:00 GMT";
    }
}

Note that this code has two limitations:

• It will not delete cookies with HttpOnly flag set, as the HttpOnly flag disables Javascript's access to the cookie.
• It will not delete cookies that have been set with a Path value. (This is despite the fact that those cookies will appear in document.cookie, but you can't delete it without specifying the same Path value with which it was set.)

The following code will remove all cookies within the current domain and all trailing subdomains (www.some.sub.domain.example, .some.sub.domain.example, .sub.domain.example and so on.).

A single line vanilla JS version (I think the only one here without the use of cookie.split()):

document.cookie.replace(/(?<=^|;).+?(?=\=|;|$)/g, name => location.hostname.split('.').reverse().reduce(domain => (domain=domain.replace(/^\.?[^.]+/, ''),document.cookie=`${name}=;max-age=0;path=/;domain=${domain}`,domain), location.hostname));

This is a readable version of this single line:

document.cookie.replace(
  /(?<=^|;).+?(?=\=|;|$)/g,
  name => location.hostname
    .split(/\.(?=[^\.]+\.)/)
    .reduceRight((acc, val, i, arr) => i ? arr[i]='.'+val+acc : (arr[i]='', arr), '')
    .map(domain => document.cookie=`${name}=;max-age=0;path=/;domain=${domain}`)
);

As far as I know there's no way to do a blanket delete of any cookie set on the domain. You can clear a cookie if you know the name and if the script is on the same domain as the cookie.

You can set the value to empty and the expiration date to somewhere in the past:

var mydate = new Date();
mydate.setTime(mydate.getTime() - 1);
document.cookie = "username=; expires=" + mydate.toGMTString(); 

There's an excellent article here on manipulating cookies using javascript.

If you are concerned about clearing cookies only on a secured origin you can use the Cookie Store API and it's .delete() method.

cookieStore.getAll().then(cookies => cookies.forEach(cookie => {
    console.log('Cookie deleted:', cookie);
    cookieStore.delete(cookie.name);
}));

Visit the caniuse.com table for the Cookie Store API to check for browser support.

Simpler. Faster.

function deleteAllCookies() {
 var c = document.cookie.split("; ");
 for (i in c) 
  document.cookie =/^[^=]+/.exec(c[i])[0]+"=;expires=Thu, 01 Jan 1970 00:00:00 GMT";    
}

I don't know why the first voted answer doesn't work for me.

As this answer said:

There is no 100% solution to delete browser cookies.

The problem is that cookies are uniquely identified by not just by their key "name" but also their "domain" and "path".

Without knowing the "domain" and "path" of a cookie, you cannot reliably delete it. This information is not available through JavaScript's document.cookie. It's not available through the HTTP Cookie header either!

So my idea is to add a Cookie version control with the full set of setting, getting, removing of cookies:

var cookie_version_control = '---2018/5/11';

function setCookie(name,value,days) {
    var expires = "";
    if (days) {
        var date = new Date();
        date.setTime(date.getTime() + (days*24*60*60*1000));
        expires = "; expires=" + date.toUTCString();
    }
    document.cookie = name+cookie_version_control + "=" + (value || "")  + expires + "; path=/";
}

function getCookie(name) {
    var nameEQ = name+cookie_version_control + "=";
    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,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
    }
    return null;
}

function removeCookie(name) {   
    document.cookie = name+cookie_version_control+'=; Max-Age=-99999999;';  
}

I have some more sophisticated and OOP-oriented cookie control module. It also contains deleteAll method to clear all existing cookie. Make notice that this version of deleteAll method has setting path=/ that causes deleting of all cookies within current domain. If you need to delete cookies only from some scope you will have to upgrade this method my adding dynamic path parameter to this method.

There is main Cookie class:

import {Setter} from './Setter';

export class Cookie {
    /**
     * @param {string} key
     * @return {string|undefined}
     */
    static get(key) {
        key = key.replace(/([\.$?*|{}\(\)\[\]\\\/\+^])/g, '\\$1');

        const regExp = new RegExp('(?:^|; )' + key + '=([^;]*)');
        const matches = document.cookie.match(regExp);

        return matches
            ? decodeURIComponent(matches[1])
            : undefined;
    }

    /**
     * @param {string} name
     */
    static delete(name) {
        this.set(name, '', { expires: -1 });
    }

    static deleteAll() {
        const cookies = document.cookie.split('; ');

        for (let cookie of cookies) {
            const index = cookie.indexOf('=');

            const name = ~index
                ? cookie.substr(0, index)
                : cookie;

            document.cookie = name + '=;expires=Thu, 01 Jan 1970 00:00:00 GMT;path=/';
        }
    }

    /**
     * @param {string} name
     * @param {string|boolean} value
     * @param {{expires?:Date|string|number,path?:string,domain?:string,secure?:boolean}} opts
     */
    static set(name, value, opts = {}) {
        Setter.set(name, value, opts);
    }
}

Cookie setter method (Cookie.set) is rather complex so I decomposed it into other class. There is code of this one:

export class Setter {
    /**
     * @param {string} name
     * @param {string|boolean} value
     * @param {{expires?:Date|string|number,path?:string,domain?:string,secure?:boolean}} opts
     */
    static set(name, value, opts = {}) {
        value = Setter.prepareValue(value);
        opts = Setter.prepareOpts(opts);

        let updatedCookie = name + '=' + value;

        for (let i in opts) {
            if (!opts.hasOwnProperty(i)) continue;

            updatedCookie += '; ' + i;

            const value = opts[i];

            if (value !== true)
                updatedCookie += '=' + value;
        }

        document.cookie = updatedCookie;
    }

    /**
     * @param {string} value
     * @return {string}
     * @private
     */
    static prepareValue(value) {
        return encodeURIComponent(value);
    }

    /**
     * @param {{expires?:Date|string|number,path?:string,domain?:string,secure?:boolean}} opts
     * @private
     */
    static prepareOpts(opts = {}) {
        opts = Object.assign({}, opts);

        let {expires} = opts;

        if (typeof expires == 'number' && expires) {
            const date = new Date();

            date.setTime(date.getTime() + expires * 1000);

            expires = opts.expires = date;
        }

        if (expires && expires.toUTCString)
            opts.expires = expires.toUTCString();

        return opts;
    }
}

document.cookie.split(";").forEach(function(c) { 
    document.cookie = c.replace(/^ +/, "").replace(/=.*/, "=;expires=" + new Date().toUTCString() + ";path=/"); 
});
//clearing local storage
localStorage.clear();

You can get a list by looking into the document.cookie variable. Clearing them all is just a matter of looping over all of them and clearing them one by one.

Several answers here do not resolve the path question. I believe that: if you control the site, or part of it, you should know all the paths used. So you just have to have it delete all cookies from all paths used. Because my site already has jquery (and out of laziness) I decided to use the jquery cookie, but you can easily adapt it to pure javascript based on the other answers.

In this example I remove three specific paths that were being used by the ecommerce platform.

let mainURL = getMainURL().toLowerCase().replace('www.', '').replace('.com.br', '.com'); // i am a brazilian guy
let cookies = $.cookie();
for(key in cookies){
    // default remove
    $.removeCookie(key, {
        path:'/'
    });
    // remove without www
    $.removeCookie(key, {
        domain: mainURL,
        path: '/'
    });
    // remove with www
    $.removeCookie(key, {
        domain: 'www.' + mainURL,
        path: '/'
    });
};

// get-main-url.js v1
function getMainURL(url = window.location.href){
    url = url.replace(/.+?\/\//, ''); // remove protocol
    url = url.replace(/(\#|\?|\/)(.+)?/, ''); // remove parameters and paths
    // remove subdomain
    if( url.split('.').length === 3 ){
        url = url.split('.');
        url.shift();
        url = url.join('.');
    };
    return url;
};

I changed the .com site to .com.br because my site is multi domain and multi lingual

I'm contributing here because this function will allow you to delete all cookies (matching the path, by default no-path or \) also cookies that were set to be included on subdomains

function clearCookies( wildcardDomain=false, primaryDomain=true, path=null ){
  pathSegment = path ? '; path=' + path : ''
  expSegment = "=;expires=Thu, 01 Jan 1970 00:00:00 GMT"
  document.cookie.split(';').forEach(
    function(c) { 
      primaryDomain && (document.cookie = c.replace(/^ +/, "").replace(/=.*/, expSegment + pathSegment))
      wildcardDomain && (document.cookie = c.replace(/^ +/, "").replace(/=.*/, expSegment + pathSegment + '; domain=' + document.domain))
    }
  )
} 

If you'd like to use js-cookie npm package and remove cookies by name:

import cookie from 'js-cookie'

export const removeAllCookiesByName = (cookieName: string) => {
  const hostParts = location.host.split('.')
  const domains = hostParts.reduce(
    (acc: string[], current, index) => [
      ...acc,
      hostParts.slice(index).join('.'),
    ],
    []
  )
  domains.forEach((domain) => cookie.remove(cookieName, { domain }))
}

We can do it like so:

deleteAllCookies=()=>
      {
      let c=document.cookie.split(';')
      for(const k of c)
         {
         let s=k.split('=')
         document.cookie=s[0].trim()+'=;expires=Fri, 20 Aug 2021 00:00:00 UTC'
         }
      }

Usage:

deleteAllCookies()

• the expiration date was a random day prior to this answer; it can be any date before the current day
• In JS you cannot read through cookies based on path
• In JS you can only set or get cookies