如何使用更新按钮使用JavaScript函数更改输入字段的文本？

Question

I am doing an assignment to update a text field when an update button is pressed so far. My code looks like this:

function updatePhotoInfo(){

var retrieve_images_script = SERVER + "/image.php?username="+USERNAME;
//@ToDo
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (xhttp.readyState == 4 && xhttp.status == 200) {
imageData= JSON.parse(xhttp.responseText);
console.log(imageData.length); 
}
};
xhttp.open("GET", retrieve_images_script, false);
xhttp.send();

var dField = document.getElementsByClassName("dField").innerHTML;
var updateField = document.getElementsByClassName("dField").new.innerHTML;
console.log("dField");

if (dField != updateField) {
dField == updateField;
};

Answer 1

So generally what I would do is the following. Say we have a button with ID=my-btn

document.getElementsByID('my-btn').onclick = function(){
  //If the name of your text filed ID is my-txt
  document.getElementsByID('my-txt').innerHTML = "DONE!"

}

This is one way to do it, but if you have the option take a looking into jquery. It makes this kind of stuff a lot easier to manage.

See this Pen for details CODE PEN

EDIT: This one includes a field: SAME WITH Field