How i can get real time value from webserver?

MIT App Inventor Help
1

I made temperature sensor webserver with esp8266.I want to display temperature value from webserver that changes in real time in label and value to put later make a chart. This is my webserver code:

const char html_page[] PROGMEM = R"rawSrting(
<!DOCTYPE html>
<html>
  <style>
    body {font-family: sans-serif;}
    h1 {text-align: center; font-size: 30px;}
    p {text-align: center; color: #4CAF50; font-size: 40px;}
  </style>

<body>
  <h1>DS18B20 Temperature Monitoring With Nodemcu</h1><br>
  <p id="TempValue"><span id="TempValue">0</span></p><br>

  <script>
    setInterval(function() {
      var xhttp = new XMLHttpRequest();
     xhttp.onreadystatechange = function() {
        if (this.readyState == 4 && this.status == 200) {
          document.getElementById("TempValue").innerHTML = this.responseText;
        }
      };
     xhttp.open("GET", "readTemp", true);
      xhttp.send();
    },50);
  </script>
</body>
</html>
)rawSrting";

I tried this:

obraz
obraz818×423 19.3 KB

window.AppInventor.setWebViewString(document.getElementsById("TempValue")[0].innerText)

But it don't change the label text at all. I also unsuccsefully tried with reload url on timer.

How i can do this?

2

Why not set the webviewstring in your html ?

...
document.getElementById("TempValue").innerHTML = this.responseText;
if(AppInventor) {
window.AppInventor.setWebViewString(this.responseText);
}
...

then in your blocks just use the WebViewStringChanged block, and add values to a list for processing. No need for the PageLoaded event.

Are you sure you want to capture the data 20 times a second ?