Robert Knight robertknight

Hypothesis and canonical links

What are canonical links?

A <link rel="canonical" href="{url}"> tag in the <head> of a page specifies the canonical/"main" URL for the current page. When the same content can be accessed at different URLs, it specifies the preferred URL for the page. It was originally introduced for use with search engines.

For example, https://www.smore.com/577k7, https://www.smore.com/577k7-whatever and https://www.smore.com/577k7-the-edtech-monthly all return the same page. That page has a <link rel=canonical> field which specifies https://www.smore.com/577k7-the-edtech-monthly as the preferred URL.

See also https://en.wikipedia.org/wiki/Canonical_link_element.

VitalSource assignments in the LMS are different than other assignment types because the document is being displayed in a reader maintained by a third-party (VitalSource) rather than Via. This third-party reader always tries to load the production version of Hypothesis, whereas when Via is used to deliver a document, your local instance of Via will use your local Hypothesis client. A workaround for this issue to enable local testing is to redirect the request for the client's boot script to point to your local client, and modify the local client to ignore parts of the Hypothesis configuration in the page where the client's boot script is loaded.

The approach documented here can also be used in other situations where you want to subtitute the production Hypothesis client with the local one, in a page or web application where we can't modify the script tag that loads the client.

Configure your browser to redirect requests for the client's boot script at https://hypothes.is/embed.js to http://localhost:5000

Hypothesis frontend project license report

This report lists the direct npm dependencies of the main Hypothesis frontend projects. See this internal Hypothesis Slack thread.

How to generate the report

The data below was generated using https://github.com/ironSource/license-report, with the following license-report-config.json configuration file:

This is a brain-dump of remaining work to achieve a fully accessible [1] Hypothesis client.

[1] fully accessible means that you can use all the functionality with a keyboard (or keyboard-emulating input device) and screen reader (or other assistive tech) conveniently and that it meets (both in letter and spirit) all the WCAG criteria. That doesn't necessarily mean that everything is as fully optimized as it could be (eg. in terms of what keyboard shortcuts are available to speed up various workflows).

Development tasks:

Make it possible to activate highlights with the keyboard
Make it easier to execute Annotate / Highlight commands using the keyboard

How I review dependency updates

These are some notes on my process when I review dependency updates for both JavaScript and Python projects at Hypothesis.

Before you add a dependency

Before adding a dependency to a project, consider the impact on future maintenance. If what the dependency does for the project can be implemented with only a few lines of code, or can be implemented in an alternative way using dependencies the project already has, it may be a better choice to do that and avoid the dependency.

	<html>
	<title>Canvas drawImage EXIF orientation test</title>
	<style>
	#dropZone {
	width: 300px;
	height: 100px;
	background-color: #aaa;
	border: 1px solid #ccc;
	}

	import os
	import sys


	def process_private_memory(pid):
	smaps_path = f"/proc/{pid}/smaps"
	total = 0
	for line in open(smaps_path, 'r'):
	field, val = [val.strip() for val in line.split(':')]
	if field != "Private_Dirty":

	/* global process */

	'use strict';

	const fs = require('fs');
	const { basename } = require('path');

	const escapeHtml = require('escape-html');
	const htmlParser = require('htmlparser2');
	const prettier = require('prettier');

	import sys
	import time
	import unicodedata


	def gen_charmap_new():
	current_cat = None
	current_cat_start = None
	ranges = []

-import sys
-files = sys.argv[1:]
-for path in files:
-    print(f"Updating {path}")
-    out_lines = []
-    prev_line_was_future_import = False
-    with open(path) as file: