I'm answering my own question. First I create a regular html input.

<input type='file'/>

I'm using React, so I use onChange attribute in place of id.
So, when the user enters with the file, a function is activated and I use the following code to get the file:

const file = event.target.files[0];

file not has a path, which is used by PDF.JS to get the real file.
Then I use a FileReader to convert the file int a Array of bits (I guess):

const fileReader = new FileReader();

Then we set a function at fileReader.onload the function can be found here

fileReader.onload = function() {...}

Finally we do this:

fileReader.readAsArrayBuffer(file);

Important PS: pdf.pdfInfo must be replaced with pdf at new PDF.JS versions.

Thanks for helping.

Extra PS: To use pdfjsLib as PDFJS in React I did this in index.html file:

window.PDFJS = pdfjsLib