hterm/nassh: Add basic support for announcing command output to AT in hterm.

This adds basic support for announcing command output for Assistive
Technology. A live region is created and <p> elements added to it to
indicate that the screen reader should announce the output. The live
region is separate from the <x-screen> element is used because not all
output will be rendered to the <x-screen>. It also allows the output to
be structured in a way that is more suitable for AT.

For large amounts of output, delays are inserted before rendering text
to the live region to avoid performance issues which cause the DOM to

nassh and crosh are updated to use this support only when a screen
reader is detected to be present. When that's not the case we don't
add nodes to the live region since there is an associated performance

Change-Id: I9ab09a4bc869038d22d907097e8d80d57d904710
Bug: 822490, 646690
Reviewed-by: David Tseng <>
Reviewed-by: Mike Frysinger <>
Tested-by: Raymes Khoury <>
13 files changed
tree: 5253e2adeb04515ca7551434f1e516bb7ec077d2
  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.