What does this* error mean?


*Uncaught TypeError: strMid.substr is not a function.
line 13 column 91

Being generated in the following test program. If I remove the “mid” statement, there is no error. It looks like “m” is coming in as NOT a string??? If not a string, how do I convert “m” from whatever it is to a string?

Test_Hamburger.nsx (29.9 KB)

Windows 10, Chrome, AppStudio vs 6272…


To figure out more, open the Chrome Debugger window. It will where the error is coming from.

Also useful is the console.log statement - you can use that to look at the value of n which you are passing into FuHamburger.


You might also have a look at the docs for Hamburger to check if you are doing things propertly:



Try this:

If typeof(m) == “object” Then return

But don’t write Return (don’t know why).


When I first used If typeof(m) == "object" Then Return I got an error message saying the “Return” was not defined… but when I used “return” (NOT capitalized), it worked correctly… thank you for that, the wiki documentation example needs to be changed.

And when I ran it (same program as uploaded on here) but with the code you suggested… clicking on hamburger #1 opened the hamburger and clicking on an entry (#3) jumped to that entry… Oh Joy!

But a second click on an entry (#2) from Form3 resulted in the same error that I first identified at the start of this thread.

I’ll now attempt what George suggested.

Thanks again


Docs fixed - darn autocorrect!


Thanks for Documentation update… helps :slight_smile:

When I ran with console.log… the log showed:

hfunc.js:13 Uncaught TypeError: strMid.substr is not a function
    at Mid (hfunc.js:13)
    at FuHamburger (code.js:10)
    at HTMLDivElement.Hamburger3.onclick (code.js:24)
Mid @ hfunc.js:13
FuHamburger @ code.js:10
Hamburger3.onclick @ code.js:24

I have no idea what this means nor what to do about it.
I’ve reloaded the test program…
Test_Hamburger.nsx (30.0 KB)


One other point… When the program initiates with Form 1, it works correctly when:

  • click on Hamburger 1 and
  • click on item 2 and/or item 3 >> a jump to Form 2 or Form 11 (as it should)
  • but a click on the Hamburger in that new form results in the error.

However, when program initiates with Form 3 or Form 11 (as the uploaded program does), a click on the Hamburger IMMEDIATELY results in the error.


Found it… Must have the ‘If typeof(m) == "object" Then return’ code immediately after the opening of the Hamburger… I hadn’t put it on Form2 nor Form11


Yes, that is vital. The click gets two events - this is to make sure you handle the one you really want.