//Updates register table and redirects back to landing page for next steps....
async function stateRedirect() { //wait until you hear back from external server.... so put async
    // Then we repackage these variables into dataToSend...
    var dataToSend = {};
    dataToSend.SubjectId = SubjectId;
    dataToSend.State = 7;
                        
    // Now we send dataToSend to our amazing PHP script...
    var dataPromise = await fetch('../RecordState.php', {
	    method: 'post',
        headers: {'Accept': 'application/json','Content-Type': 'application/json'},
        body: JSON.stringify(dataToSend)});

    // Finally, we can redirect the participant to the external task...
    var dataSentBack = await dataPromise.json();
    var allIsWell = dataSentBack.allIsWell;
    if (allIsWell) {
	    window.location.href = `https://do3.thinkcognito.org.uk/index.html?SubjectId=${SubjectId}`;
    }
}  


<div class="button-container">
                    <button onclick="nextTask()" class="button">Next Task</button>
                </div>