JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://api.trello.com/1/client.js?key=00f1dd1e00000f1dd1e00000f1dd1e00&amp;dummy=.js"></script>
<div id="loggedout">
    <a id="connectLink" href="#">Connect To Trello</a>
</div>

<div id="loggedin">
    <div id="header">
        Logged in to as <span id="fullName"></span> 
        <a id="disconnect" href="#">Log Out</a>
    </div>
    
    <div id="upload">
        <form action="https://api.trello.com/1/cards/REPLACE_WITH_CARD_ID/attachments" method="POST" enctype="multipart/form-data" 
        target="uploader">
            <input type="hidden" id="key" name="key" value="" />
            <input type="hidden" id="token" name="token" value="" />
            <input type="file" name="file">
            <input type="submit" value="Upload">
        </form>
        <iframe name="uploader"></iframe>
    </div>
</div>

CSS

body {
    font-family: arial;
    font-size: 12px;
}

#loggedout {
    text-align: center;
    font-size: 20px;
    padding-top: 30px;
}
#loggedin { 
    display: none; 
}

#header {
    padding: 4px;
    border-bottom: 1px solid #000;
    background: #eee;
}

#upload {
    padding: 4px;
}

.card { 
    display: block; 
    padding: 2px;
}

JavaScript

/* 
NOTE: The Trello client library has been included as a Managed Resource.  To include the client library in your own code, you would include jQuery and then

NOTE: You'll need to update the action part of the form to include the id of a card that you own

<script src="https://api.trello.com/1/client.js?key=your_application_key">...

See https://trello.com/docs for a list of available API URLs

The API development board is at https://trello.com/api

The &dummy=.js part of the managed resource URL is required per http://doc.jsfiddle.net/basic/introduction.html#add-resources
*/

var onAuthorize = function() {
    updateLoggedIn();
    $("#key").val(Trello.key());
    console.log(Trello.key());
    $("#token").val(Trello.token());
};

var updateLoggedIn = function() {
    var isLoggedIn = Trello.authorized();
    $("#loggedout").toggle(!isLoggedIn);
    $("#loggedin").toggle(isLoggedIn);        
};
    
var logout = function() {
    Trello.deauthorize();
    updateLoggedIn();
};
                          
Trello.authorize({
    interactive:false,
    success: onAuthorize
});

$("#connectLink")
.click(function(){
    Trello.authorize({
        type: "popup",
        scope: { read: true, write: true },
        success: onAuthorize
    })
});
    
$("#disconnect").click(logout);