Google Apps Script Typeerror: Cannot Call Method "substring" Of Undefined

I have a google form that when submitted calls an 'on form submit' function that includes javascript .substring(start,finish) method. The strange thing is that in my testcode it w

Solution 1:

no pro here per se, but I think I have a hunch on what the issue is.

vararray = ["aaa", "bbb", "ccc"];

for (var i = 0; i <= array.length; i++) {
    console.log(array[i]);
}

See when running the above code, I'll get a console.log at the end with undefined, due to the i <= array.length.

Running a string method like .substring on undefined throws the error.

Change the <= to a < and you should be good to go.