How to Use pdf.js

I am considering using pdf.js (an open source tool that allows embedding of a pdf in a webpage). There isn't any documentation on how to use it.

I assume what I do is make an html page with the script referenced in the header, and then in the body, I put some sort of function call with an array of the file name and location. Can anyone help me out here?

There is documentation available on their github readme. They cite the following example code:

/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */

//
// See README for overview
//

'use strict';

//
// Fetch the PDF document from the URL using promises
//
PDFJS.getDocument('helloworld.pdf').then(function(pdf) {
  // Using promise to fetch the page
  pdf.getPage(1).then(function(page) {
    var scale = 1.5;
    var viewport = page.getViewport(scale);

    //
    // Prepare canvas using PDF page dimensions
    //
    var canvas = document.getElementById('the-canvas');
    var context = canvas.getContext('2d');
    canvas.height = viewport.height;
    canvas.width = viewport.width;

    //
    // Render PDF page into canvas context
    //
    var renderContext = {
      canvasContext: context,
      viewport: viewport
    };
    page.render(renderContext);
  });
});

Try Google'ing pdf.js documentation

/* create the PDF document */

var doc = new pdf();
doc.text(20, 20, 'hello, I am PDF.');
doc.text(20, 30, 'i was created in the browser using javascript.');
doc.text(20, 40, 'i can also be created from node.js');

/* Optional - set properties on the document */
doc.setProperties({
  title: 'A sample document created by pdf.js',
  subject: 'PDFs are kinda cool, i guess',        
  author: 'Marak Squires',
  keywords: 'pdf.js, javascript, Marak, Marak Squires',
  creator: 'pdf.js'
});
      
doc.addPage();
doc.setFontSize(22);
doc.text(20, 20, 'This is a title');
doc.setFontSize(16); 
doc.text(20, 30, 'This is some normal sized text underneath.');

var fileName = "testFile"+new Date().getSeconds()+".pdf";
var pdfAsDataURI = doc.output('datauri', {"fileName":fileName});

NOTE: the "pdf.js" project mentioned here is https://github.com/Marak/pdf.js, and has been deprecated since this answer was posted. @Treffynnon's answer is about the still-active Mozilla project (https://github.com/mozilla/pdf.js) that most searchers will be looking for.