Axios 401 response interceptor.

axios-401-response-interceptor.js

// Add a 401 response interceptor
window.axios.interceptors.response.use(function (response) {
    return response;
}, function (error) {
    if (401 === error.response.status) {
        swal({
            title: "Session Expired",
            text: "Your session has expired. Would you like to be redirected to the login page?",
            type: "warning",
            showCancelButton: true,
            confirmButtonColor: "#DD6B55",
            confirmButtonText: "Yes",
            closeOnConfirm: false
        }, function(){
            window.location = '/login';
            
            return Promise.reject(error)
        });
    } else {
        return Promise.reject(error);
    }
});

Watch out for false positives: If you use the same Axios instance to query other domains than your back end and that domain responds with status 401 your code will trigger.

Consider using a dedicated Axios instance to query other domains, or add something like that to the if (401 === error.response.status) condition:
&& isSameOrigin(error.response.request.responseURL)

/**
 * @param {string} url
 * @return {boolean}
 */
const isSameOrigin = url => {
    return new URL(window.location.href).origin === new URL(url).origin;
}

Good Point. Thanks.

I have a question?
What should I do if the API returns the 401 error code when the password does not match?

@hungpurdie You need the API to tell you that 401 is because of password mismatch specifically. In the following example the API responds 401 with a "Bad credentials." message only in that specific case:

axios.interceptors.response.use(
    response => {
        return response;
    },
    error => {
        if (
            isSameOrigin(error.response?.request?.responseURL)
            && error.response?.status === 401
            && error.response?.data?.message !== 'Bad credentials.'
        ) {
            // Do something
        }

        return Promise.reject(error);
    }
);

In case of redirect to login page you do not fulfill the promise. You must return Promise.reject(error); after window.location

Agreed. return Promise.reject(error) needs to be called no matter what.

Gist adjusted and included the reject call. Thanks!

Awesome, great work!