Run mix format on all unstaged Elixir files

git ls-files -m | awk '/\.[ex|exs]/' | xargs mix format {}

ExUnit - rerun only failed tests

This will only run tests which failed the last time:

mix tests --failed

There are far more useful options listed under mix help test

Decrease bundle size by importing Lodash correctly

If you use just one or a few Lodash functions in a file, try importing them directly from their respective files, one by one.

import _ from 'lodash'; // bad - 70.5K (gzipped: 24.4K)
import { has } from 'lodash'; // bad - 70.5K (gzipped: 24.4K)

import has from 'lodash/has'; // good - 9K (gzipped: 2.7K)

Alternatively, one can use babel-plugin-lodash or lodash-es. These packages come with sets of restrictions though.

It is worth noting that mixing these 2 import styles will cause the net gain to be negative. Basically, it will import the entire lodash + individual utilities twice. So, for this to be effective, the ‘good’ pattern needs to be enforced everywhere across the codebase.

Further reading