File Zipper Project using Huffman Encoder

Sir I was doing the File Zipper project using Huffman Encoder and I am getting the following error. Could you please solve it?
I’ve attached the images

“Uncaught SyntaxError: Unexpected token ‘export’ heap.js:1
Uncaught SyntaxError: Cannot use import statement outside a module huffman.js:1
Uncaught SyntaxError: Cannot use import statement outside a module script.js:1”

I have written the same code as yours! Took a ss but can’t attach more than 1 image.
It would mean a lot if you would solve this problem for me
Thankyou in advance!