How to find duplicate id's in a form?

Question

I\'ve created a form with about 800 fields in it. Unknowingly I\'ve given same id for few fields in the form. How to trace them?

Answer 1

I've created an example for you to have a look at, it finds all of the duplicate IDs within a form/element on a page and prints the duplicates ID names to the console.

The array contains method was taken from this post.

The above code will output the following:

Duplicate: a

Duplicate: d