JSFiddle - React, Tailwind, and code Playground

JavaScript

function getUserId(){
    var url = "http://api.flickr.com/services/rest/?jsoncallback=?&api_key=fc6c52ed4f458bd9ee506912a860e466&method=flickr.urls.lookupUser&format=json&nojsoncallback=1&url=http://www.flickr.com/photos/flickr";
    var getUsername = null;
    
    $.ajax({
        dataType:'jsonp',
        url: url,
        async:false,
        success: function(data){
            getUsername = data.user.id;
        },
    });

    return getUsername;
}

$(document).ready(function(){
    alert(getUserId());    
})