B4J Question RunFunction with browser error

jkhazraji · Dec 17, 2021

Hello everybody,
I want to run a Javascript function that I introduced by ws.Eval into the server, by clicking a button on the html page that I captured in the app as JQueryElement.
So I want the function to run in the click event of the button in server app as shown in the code section. However, it does not with an error in the console that states:
Uncaught TypeError: Cannot read properties of undefined (reading 'apply')
at b4j_runFunction (b4j_ws.js:51)
at WebSocket.b4j_ws.onmessage (b4j_ws.js:79)

The code:

B4X:

.
Private sub somefunc()
.
.

Dim code As String = $"
                 function hi(str){
               
                   alert(str);
                 }
                    "$
    ws.Eval(code,Null)
    .
    .
    .
End sub
Private Sub btn_Click (Params As Map)
   
    ws.RunFunction("hi", Array As String("Hello"))
    ws.Flush
   
End Sub

Any mastemind could expalin that.. I will be grateful
Regards

alwaysbusy · Dec 17, 2021

You seem to mix two things. You either use:

B4X:

Private Sub btn_Click (Params As Map)  
    Dim code As String = $"
                 function hi(str){             
                   alert(str);
                 }"$
    ws.Eval(code,Array As String("Hello"))
    ws.flush
End Sub

OR you put the javascript code of the hi function in your .html file between <script></script> tags and then use:

B4X:

Private Sub btn_Click (Params As Map)  
    ws.RunFunction("hi", Array As String("Hello"))
    ws.Flush  
End Sub

ws.eval does not add the javascript code to your html, it is 'temporary'.

Alwaysbusy

jkhazraji · Dec 17, 2021

alwaysbusy said:
You seem to mix two things. You either use:

B4X:

Private Sub btn_Click (Params As Map) Dim code As String = $" function hi(str){ alert(str); }"$ ws.Eval(code,Array As String("Hello")) ws.flush End Sub

OR you put the javascript code of the hi function in your .html file between <script></script> tags and then use:

B4X:

Private Sub btn_Click (Params As Map) ws.RunFunction("hi", Array As String("Hello")) ws.Flush End Sub

ws.eval does not add the javascript code to your html, it is 'temporary'.

Alwaysbusy

Hi,
I tried both of your methods but I got the same error?

jkhazraji · Dec 19, 2021

alwaysbusy said:
]

ws.eval does not add the javascript code to your html, it is 'temporary'.

Alwaysbusy

I am really confused with your answer..
See:
https://www.b4x.com/android/forum/threads/webapp-hello-world-web-app.39808/

Which states:

“The WebSocket itself (ws in this case) allows you to call any JavaScript function and also to create JavaScript code at runtime and run it (eval / new function).”

ilan · Dec 19, 2021

alwaysbusy said:
You seem to mix two things. You either use:

B4X:

Private Sub btn_Click (Params As Map) Dim code As String = $" function hi(str){ alert(str); }"$ ws.Eval(code,Array As String("Hello")) ws.flush End Sub

OR you put the javascript code of the hi function in your .html file between <script></script> tags and then use:

B4X:

Private Sub btn_Click (Params As Map) ws.RunFunction("hi", Array As String("Hello")) ws.Flush End Sub

ws.eval does not add the javascript code to your html, it is 'temporary'.

Alwaysbusy

if you define a function then you need to call it.

this should work.

B4X:

    Dim str As String = "Hello"
    Dim code As String = $"alert('${str}');"$
    ws.Eval(code,Null)
    ws.flush

alwaysbusy · Dec 19, 2021

You are absolutely correct. Wrote it without testing and my example is wrong. Ilan's way is how it must be done

jkhazraji · Dec 19, 2021

alwaysbusy said:
You are absolutely correct. Wrote it without testing and my example is wrong. Ilan's way is how it must be done

?

B4J Question RunFunction with browser error

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B4J Question RunFunction with browser error

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