hterm: Add skip-links to allow screen readers to scroll the terminal

This adds two buttons to the terminal, one at the top and one at the
bottom to scroll the terminal up/down respectively. These buttons are
not normally visible (being hidden off-screen). However when the buttons
are selected (e.g. by a screen reader) they will appear on-screen and
can be used to navigate through the history of the terminal.

The scroll up button appears immediately prior to the first on-screen
row of the terminal. Similarly the scroll down button appears
immediately after the last on-screen row. This means that when
navigating using a screen reader it will be the first thing that is hit
prior to navigating off the edge of the terminal.

Bug: 822490, 646690
Change-Id: Ie71f3ef5051a1b05b63e01ead29ce52db8a31230
Tested-by: Raymes Khoury <>
Reviewed-by: Mike Frysinger <>
5 files changed
tree: 56d276e0a37717c32bdfbf5d77b1b47af4e11ad7
  1. .clang-format
  2. .eslintrc.js
  3. .gitignore
  7. hterm/
  8. libdot/
  9. nassh/
  11. package.json
  12. saltpig/
  13. ssh_client/
  14. wam/
  15. wash/


This repository contains the libdot JavaScript library and some web applications that make use of it.

The official copy of this repository is hosted at

There is also a mirror on github at A few subprojects are also extracted out into their own git repo and mirrored. Keep in mind that these mirrors may occasionally be behind the official repository.

All changes must go through the Gerrit code review server on Github pull requests cannot be accepted. Please see the document in this directory for the details.

Top level directories

  • libdot/ is a small set of JS libraries initially developed as part of hterm, now available as shared code.

  • hterm/ is a JS library that provides a terminal emulator. It is reasonably fast, reasonably correct, and reasonably portable across browsers.

  • nassh/ is the Secure Shell Chrome App (currently a “v1.5” app, soon to become a “v2” or platform app) that combines hterm with a NaCl build of OpenSSH to provide a PuTTY-like app for Chrome users.

  • ssh_client/ is the NaCl port of OpenSSH. It is used by nassh to create the Secure Shell App.

  • wash/ is a library for cross-origin virtual filesystems, similar to the Plan 9 filesystem. This directory also contains a simple bash-like shell environment for exploring these filesystems. The code in this directory is a work-in-progress.