发送https://invalid_login@hostname在任何地方都可以工作，除了Mac上的Safari(好吧，没有勾选Edge，但也应该工作)。

当用户在HTTP基本身份验证弹出框中选择“记住密码”时，Safari中的注销不工作。在这种情况下，密码存储在Keychain Access (Finder > Applications > Utilities > Keychain Access(或CMD+SPACE并键入“Keychain Access”))中。发送https://invalid_login@hostname不会影响钥匙链访问，所以这个复选框不可能在Mac上的Safari上注销。至少它是如何为我工作的。

MacOS Mojave (10.14.6)， Safari 12.1.2。

下面的代码在Firefox(73)、Chrome(80)和Safari(12)中运行良好。当用户导航到登出页面时，执行代码并删除凭据。

    //It should return 401, necessary for Safari only
    const logoutUrl = 'https://example.com/logout'; 
    const xmlHttp = new XMLHttpRequest();
    xmlHttp.open('POST', logoutUrl, true, 'logout');
    xmlHttp.send();

此外，由于某些原因，Safari不会在HTTP基本身份验证弹出框中保存凭据，即使选择了“记住密码”。其他浏览器可以正确地做到这一点。

此JavaScript必须适用于所有最新版本的浏览器:

//Detect Browser
var isOpera = !!window.opera || navigator.userAgent.indexOf(' OPR/') >= 0;
    // Opera 8.0+ (UA detection to detect Blink/v8-powered Opera)
var isFirefox = typeof InstallTrigger !== 'undefined';   // Firefox 1.0+
var isSafari = Object.prototype.toString.call(window.HTMLElement).indexOf('Constructor') > 0;
    // At least Safari 3+: "[object HTMLElementConstructor]"
var isChrome = !!window.chrome && !isOpera;              // Chrome 1+
var isIE = /*@cc_on!@*/false || !!document.documentMode; // At least IE6
var Host = window.location.host;


//Clear Basic Realm Authentication
if(isIE){
//IE
    document.execCommand("ClearAuthenticationCache");
    window.location = '/';
}
else if(isSafari)
{//Safari. but this works mostly on all browser except chrome
    (function(safeLocation){
        var outcome, u, m = "You should be logged out now.";
        // IE has a simple solution for it - API:
        try { outcome = document.execCommand("ClearAuthenticationCache") }catch(e){}
        // Other browsers need a larger solution - AJAX call with special user name - 'logout'.
        if (!outcome) {
            // Let's create an xmlhttp object
            outcome = (function(x){
                if (x) {
                    // the reason we use "random" value for password is 
                    // that browsers cache requests. changing
                    // password effectively behaves like cache-busing.
                    x.open("HEAD", safeLocation || location.href, true, "logout", (new Date()).getTime().toString())
                    x.send("");
                    // x.abort()
                    return 1 // this is **speculative** "We are done." 
                } else {
                    return
                }
            })(window.XMLHttpRequest ? new window.XMLHttpRequest() : ( window.ActiveXObject ? new ActiveXObject("Microsoft.XMLHTTP") : u )) 
        }
        if (!outcome) {
            m = "Your browser is too old or too weird to support log out functionality. Close all windows and restart the browser."
        }
        alert(m);
        window.location = '/';
        // return !!outcome
    })(/*if present URI does not return 200 OK for GET, set some other 200 OK location here*/)
}
else{
//Firefox,Chrome
    window.location = 'http://log:out@'+Host+'/';
}

添加到你的应用程序:

@app.route('/logout')
def logout():
    return ('Logout', 401, {'WWW-Authenticate': 'Basic realm="Login required"'})

function logout() {
  var userAgent = navigator.userAgent.toLowerCase();

  if (userAgent.indexOf("msie") != -1) {
    document.execCommand("ClearAuthenticationCache", false);
  }

  xhr_objectCarte = null;

  if(window.XMLHttpRequest)
    xhr_object = new XMLHttpRequest();
  else if(window.ActiveXObject)
    xhr_object = new ActiveXObject("Microsoft.XMLHTTP");
  else
    alert ("Your browser doesn't support XMLHTTPREQUEST");

  xhr_object.open ('GET', 'http://yourserver.com/rep/index.php', false, 'username', 'password');
  xhr_object.send ("");
  xhr_object = null;

  document.location = 'http://yourserver.com'; 
  return false;
}

为了记录，有一个新的HTTP响应头叫做Clear-Site-Data。如果你的服务器回复包含一个Clear-Site-Data: "cookies"头，那么身份验证凭证(不仅仅是cookies)应该被删除。我在Chrome 77上测试了它，但控制台显示了这个警告:

Clear-Site-Data header on 'https://localhost:9443/clear': Cleared data types:
"cookies". Clearing channel IDs and HTTP authentication cache is currently not
supported, as it breaks active network connections.

并且认证凭证没有被删除，所以这不能(目前)实现基本的认证注销，但也许将来会。没有在其他浏览器上测试。

引用:

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Clear-Site-Data

https://www.w3.org/TR/clear-site-data/

https://github.com/w3c/webappsec-clear-site-data

https://caniuse.com/#feat=mdn-http_headers_clear-site-data_cookies

bobince对这个问题的补充回答是…

使用Ajax，您可以将“注销”链接/按钮连接到Javascript函数。让这个函数发送带有错误用户名和密码的XMLHttpRequest。这应该会得到401。然后设置文档。位置返回到预登录页面。这样，用户将永远不会在注销期间看到额外的登录对话框，也不必记得输入错误的凭据。