keysim.js

Simulate typing into DOM elements. This can be used anywhere you need to simulate user keystrokes, but is particularly useful in testing environments.

Installation

# Install via npm.
$ npm install [--save-dev] keysim
# Install via yarn.
$ yarn add [--dev] keysim
# Install by copying the dist file.
$ curl -o path/to/vendor/keysim.js https://unpkg.com/keysim@latest/dist/keysim.js

Usage

There are two high-level methods for simulating keystrokes on a DOM element, one for typing input into an element and one for typing non-input "action" keystrokes. Note that none of the methods provided by keysim will trigger the browser's default behavior, such as inserting text or moving the cursor. It only allows you to test your event handling code by sending the correct DOM events.

Entering Text

Get a standard keyboard and use it to fire events onto a DOM element:

let input = document.getElementById("name");
let keyboard = Keysim.Keyboard.US_ENGLISH;
keyboard.dispatchEventsForInput("hello!", input);

This will fire events keydown, keypress, keyup, and textInput events for each typed character in the input string. In addition, some characters may require modifier keys in order to type. The keydown and keyup events will be fired for these modifier keys (e.g. the SHIFT key) as appropriate. ¹

Triggering Special Actions

It is also sometimes useful to simulate special keys, or actions that do not cause input. For example, here's how to simulate backward deleting a word and selecting all text in the input:

let input = document.getElementById("name");
let keyboard = Keysim.Keyboard.US_ENGLISH;
keyboard.dispatchEventsForAction("alt+backspace", input);
keyboard.dispatchEventsForAction(`${osx ? "meta" : "ctrl"}+a`, input);

Raw Keystroke Dispatch

If you need to dispatch events for an exact sequence of keystrokes you may use Keyboard#dispatchEventsForKeystroke, which is used by both Keyboard#dispatchEventsForInput and Keyboard#dispatchEventsForAction.

let input = document.getElementById("name");
let keyboard = Keysim.Keyboard.US_ENGLISH;
let ctrl_shift_enter = new Keysim.Keystroke(
  Keysim.Keystroke.CTRL | Keysim.Keystroke.SHIFT,
  13
);
keyboard.dispatchEventsForKeystroke(ctrl_shift_enter, input);

---

¹ Here is the complete set of events fired (as reported by this page):

keydown  keyCode=72  (H)   which=72  (H)   charCode=0
keypress keyCode=104 (h)   which=104 (h)   charCode=104 (h)  
textInput data=h
keyup    keyCode=72  (H)   which=72  (H)   charCode=0
keydown  keyCode=69  (E)   which=69  (E)   charCode=0
keypress keyCode=101 (e)   which=101 (e)   charCode=101 (e)  
textInput data=e
keyup    keyCode=69  (E)   which=69  (E)   charCode=0
keydown  keyCode=76  (L)   which=76  (L)   charCode=0
keypress keyCode=108 (l)   which=108 (l)   charCode=108 (l)  
textInput data=l
keyup    keyCode=76  (L)   which=76  (L)   charCode=0
keydown  keyCode=76  (L)   which=76  (L)   charCode=0
keypress keyCode=108 (l)   which=108 (l)   charCode=108 (l)  
textInput data=l
keyup    keyCode=76  (L)   which=76  (L)   charCode=0
keydown  keyCode=79  (O)   which=79  (O)   charCode=0
keypress keyCode=111 (o)   which=111 (o)   charCode=111 (o)  
textInput data=o
keyup    keyCode=79  (O)   which=79  (O)   charCode=0
keydown  keyCode=16        which=16        charCode=0
keydown  keyCode=49  (1)   which=49  (1)   charCode=0
keypress keyCode=33  (!)   which=33  (!)   charCode=33  (!)  
textInput data=!
keyup    keyCode=49  (1)   which=49  (1)   charCode=0
keyup    keyCode=16        which=16        charCode=0
keydown  keyCode=91  ([)   which=91  ([)   charCode=0

Check out this demo page here.

Building

Ensure that the keysim dependencies are installed (npm install). Then run npm run build to re-create dist/keysim.js.

Testing

To run the tests in Chrome, run npm run test:browser. To run the tests in node, run npm run test:node. Running npm test will run both.

Contributing

Fork the project, create a branch, and fix your bug or add your feature on that branch. Be sure to add tests for your bug fix or feature.