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7.4.0 • Public • Published


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This library manages all of the inputs (mouse/keyboard events, location changes, hover information, and hover actions) necessary to display hover tooltips on with a code view. All together, this makes it easier to add code intelligence to code views on the web. Used in Sourcegraph.

What it does

  • Listens to hover and click events on the code view
  • On mouse hovers, determines the line+column position, performs a hover request, and renders it in a nice tooltip overlay at the token
  • Shows actions in the hover
  • When clicking a token, pins the tooltip to that token
  • Highlights the hovered token

You need to provide your own UI component (referred to as the HoverOverlay) that actually displays this information and exposes these actions to the user.


  • Call createHoverifier() to create a Hoverifier object (there should only be one on the page, to have only one HoverOverlay shown).
  • The Hoverifier exposes an Observable hoverStateUpdates that a consumer can subscribe to, which emits all data needed to render the HoverOverlay
  • For each code view on the page, call hoverifier.hoverify(), passing the position events coming from findPositionsFromEvents().
  • hoverify() returns a Subscription that will "unhoverify" the code view again if unsubscribed from


yarn test

# Helpful options:
yarn test -- --single-run      # Don't rerun on changes
yarn test -- --browsers Chrome # Only run in Chrome

Development is done by running tests. Karma is used to run Mocha tests in the browser. You can debug by opening http://localhost:9876/debug.html in a browser while the test running is active. The tests will rerun automatically when files are changed.

You can run specific tests by adding .only to describe or it calls.


Releases are done automatically in CI when commits are merged into master by analyzing Conventional Commit Messages. After running yarn, commit messages will be linted automatically when committing. You may have to rebase a branch before merging to ensure it has a proper commit history.


Term Definition
Code view The DOM element that contains all the line elements
Line number element The DOM element that contains the line number label for that line
Code element The DOM element that contains the code for one line
Diff part The part of the diff, either base, head or both (if the line didn't change). Each line belongs to one diff part, and therefor to a different commit ID and potentially different file path.
Hover overlay Also called tooltip
hoverify To attach all the listeners needed to a code view so that it will display overlay on hovers and clicks.
unhoverify To unsubscribe from the Subscription returned by hoverifier.hoverify(). Removes all event listeners from the code view again and hides the hover overlay if it was triggered by the unhoverified code view.




npm i @sourcegraph/codeintellify

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  • nathan-downs
  • natefreng
  • andreeleuterio
  • sourcegraph-bot
  • sqs
  • beyang
  • slimsag
  • roksg