function uploadImage()

in code/app/static/main.js [161:199]


function uploadImage(e){
    e.preventDefault();
    var xmlhttp = new XMLHttpRequest();
    let photo = document.getElementById("myFile").files[0];  // file from input
    let form  = new FormData();


    if (typeof photo == 'undefined'){
        alert('No image indicated');
        return;
    }
    
    form.append("myFile", photo);                                

    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState == XMLHttpRequest.DONE) {   // XMLHttpRequest.DONE == 4
           if (xmlhttp.status == 201) {
               // Waiting on Cloud Function to modify the images. 
               sendAlert("Processing image!");  
               setTimeout(listImages, 2000);
           }
           else if (xmlhttp.status == 500) {
            let msg = JSON.parse(xmlhttp.response);
            if (msg.error.includes("invalid image type")) {
                sendError(msg.error);
            } else {
                sendError(msg.error);
            }
           }
           else {
               alert('something else other than 201 was returned');
               console.log(xmlhttp.status);
           }
        }
    };

    xmlhttp.open("POST", basepath, true);
    xmlhttp.send(form);
}