If you try to submit a form with JavaScript and keep getting “Submit is not a function” then you probably have a field in your form named “submit”.
Take a look at your form maybe a hidden field:
<input type="text" name="submit" value="true" />
Or your submit button’s name:
<input type="submit" name="submit" />
Change the name of the field to something else and try.
This is one of those situations where you find yourself pulling your hair out 
Happy coding.
I'm the co-founder of