VB6 - Web message example
In the web message demo we use html5 web messages to communicate between Visual Basic and the html page.
You can read more about web messages here: MDN postMessage.
The html page looks like:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<link rel="StyleSheet" href="WebMessage.css" type="text/css">
<script>
function sendString(){
const textData = document.getElementById("data");
if(textData && window.chrome.webview){
window.chrome.webview.postMessage(textData.value);
}
}
function sendJSON(){
const textData = document.getElementById("data");
if(textData && window.chrome.webview){
let msg = { name : "Bob", age : 38, comment : textData.value};
window.chrome.webview.postMessage(msg);
}
}
window.chrome.webview.addEventListener('message', (event) =>{
const textData = document.getElementById("data");
if(textData){
if (typeof event.data === 'object' || typeof event.data === 'null' ) {
textData.value = JSON.stringify(event.data);
}
else {
textData.value = event.data;
}
}
});
</script>
</head>
<body>
<section class="container">
<p>Send data between HOST application and control via messages</p>
<textarea id="data">Text that you want to sent to the application hosting the browser control.</textarea>
<div>
<span>
<button id="postString" onclick="sendString();">Post String</button>
</span>
<span>
<button id="postJSON" onclick="sendJSON();">Post JSON</button>
</span>
<div>
</section>
</body>
</html>
The "Post String" button has the following code:
Private Sub PostStringButton_Click()
Dim Message As String
Message = StringTextBox.Text
EdgeWebBrowser.PostWebMessageAsString Message
End Sub
Which sets the textData.value in the html above via the event listener for message.
The "Post JSON" button does something similar.
Private Sub PostJsonButton_Click()
Dim Json As String
Json = JsonTextBox.Text
EdgeWebBrowser.PostWebMessageAsJson Json
End Sub
Communication the other way around from the html page to the Visual Basic application is via the javascript postMessage and is triggered via function sendString() or function sendJSON()
Either one raises the event OnWebMessageReceived, which has the following code:
Private Sub EdgeWebBrowser_OnWebMessageReceived(ByVal URI As String, ByVal MessageAsJson As String, ByVal MessageAsString As String)
Dim Content As String
If Trim(MessageAsJson) <> "" Then
JsonTextBox.Text = JsonTextBox.Text & vbCrLf & MessageAsJson
End If
If Trim(MessageAsString) <> "" Then
StringTextBox.Text = StringTextBox.Text & vbCrLf & MessageAsString
End If
End Sub
AntView - The MS Edge WebView2 ActiveX control Date last changed: 09/25/2024