Hello,
it looks like you already have pdf checker built in. Is it not working on some browsers? Anyway, we can implement HTML5 checker and fix pdf checker as needed. Our web development team has extensive experience with all modern web development technologies, which of course includes Javascript, hence we believe we can address your problem and deliver the project.
We look forward to hearing from you.
Regards,
Prakash,
Sr. SDE, Rooh