Install

Install via npm

npm install --save-dev jscoverage

Ignore output

echo coverage.html >> .gitignore

package.json

The coverage task injects your source files (lib) with jscoverage hooks, runs mocha -R html-cov, then restores later.
{: .-setup}

/* directory */
"coverage": "mv lib lib~; (jscoverage lib~ lib; mocha -R html-cov > coverage.html); rm -rf lib; mv lib~ lib"

{: .-hard-wrap}

/* single file */
"coverage": "(cp index.js index.js~; jscoverage index.js; mv index-cov.js index.js; mocha -R html-cov > coverage.html); mv index.js~ index.js"

{: .-hard-wrap}

Run

npm run coverage

open coverage.html

Caveats

If you’re using jsdom, be sure to expose the window._$jscoverage variable into
the global scope.