Strip trailing zeros after an interior zero in engineeringNotation

What does this MR do?

engineeringNotation removes the trailing zeros of the scaled mantissa with the pattern /\.([1-9]*)0+$/ (number_utils.js#L88). The capture group only accepts the digits 1 to 9, so the pattern cannot match a fractional part that has a zero before a nonzero digit, and the trailing zeros stay: engineeringNotation(1.05, 3) returns 1.050, engineeringNotation(1.005, 4) returns 1.0050, engineeringNotation(12000.5, 4) returns 12.0010k and engineeringNotation(0.00105, 4) returns 1.0500m, while engineeringNotation(1.5, 4) already returns 1.5.

This MR changes the group to (\d*?), a lazy match of any digits, so it keeps every digit up to the last nonzero one and drops only the zeros at the end. The four new rows in number_utils.spec.js fail without the change and pass with it. The changeset asks for a @gitlab/ui patch release.

Only a precision of 3 or more can show the bug, because the fraction needs an interior zero, a nonzero digit and a trailing zero. The charts in GitLab UI call the function with a precision of 2, passed explicitly or by default, so their output does not change. GitLab imports the function from @gitlab/ui/src/utils/number_utils, and the engineering format of getFormatter returns it as it is (unit_format/index.js#L124-125), so a caller there that passes a precision of 3 or more gets the extra zeros today.

How I verified it

On main at 4b7ad87adbf4950b01e295497c6d19c67617f0aa, with Node 22.23.3 and Yarn 1.22.22 as mise.toml pins them, after yarn install --frozen-lockfile. Test commands ran in packages/gitlab-ui, lint from the repository root.

Without the fix (only the new spec rows applied), NODE_ENV=test npx jest src/utils/number_utils.spec.js -t engineeringNotation fails the four new rows and passes the others:

Failing test	Expected	Received
with args [1.05, 3], returns 1.05	1.05	1.050
with args [1.005, 4], returns 1.005	1.005	1.0050
with args [12000.5, 4], returns 12.001k	12.001k	12.0010k
with args [0.00105, 4], returns 1.05m	1.05m	1.0500m

Tests:       4 failed, 59 skipped, 18 passed, 81 total

With the fix:

• NODE_ENV=test npx jest src/utils/number_utils.spec.js: 81 passed.
• yarn test:unit: 242 suites, 4,382 tests passed and 1 skipped.
• yarn test:unit-vue3: 241 suites passed and 1 skipped, 4,376 tests passed and 3 skipped.
• yarn lint, which runs eslint, markdownlint, prettier, stylelint and yarn-deduplicate as the lint job does: all five pass.
• ./bin/check_translations_dict.sh: the dictionary is up to date.
• npx changeset status --since=upstream/main: @gitlab/ui at patch.
• The commit went through the lefthook pre-commit and commit-msg hooks.
• The spec fails for a greedy (\d*), a single-digit (\d?) and a single-zero 0$ variant of the new pattern, each time on at least one of the new rows.
• For a precision of 0, 1 and 2, the old and new functions gave the same string in all 840,021 comparisons I ran (280,007 values between about -2e10 and 2e10 at each precision), so callers that keep the default precision see no change.

Screenshots or screen recordings

None. No component renders differently: GitLab UI's own charts format their numbers with a precision of 2.

Integrations

The function's signature and its output for a precision of 2 or less do not change, so no project needs a migration.

• GitLab: mr_url (Run the ui:create_integration_merge_request CI job, which automatically creates the merge request and updates this item for you.)
• CustomersDot: mr_url
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• Status Page: mr_url
• Docs: mr_url
• Switchboard: mr_url

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