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Scott Spence

Patching Packages with patch-package

3 min read
Hey! Thanks for stopping by! Just a word of warning, this post is about 4 years old, wow! If there's technical information in here it's more than likely out of date.

I found an opportunity to improve the npm package for the Victor Mono font I like to use here and in my text editor (much to peoples horror when they see it)!

It was a simple fix to add font-display: swap; to the css file in the dist package.

The maintainer was super responsive and added the change straight away which was cool, that doesn’t mean that the changes are going to be packaged up and released that quickly.

Looking at the releases it could be a while before this gets published to npm so I decided to give patch-package a try.

Video on patch-package

Ben Awad had a great video on how to use it with an example, check it out here:


I’m using Yarn so I installed both patch-package and postinstall-postinstall:

yarn add -D patch-package postinstall-postinstall

Make the change

In this case I want to change my victormono package, so, I can find it in the node_modules.

Check the package.json for the "main" file, Victor Mono is quite a simple project so there’s just the one dist/index.css I can take the changes made to the GitHub project and add them to my version of the package.

Patch it

Now I have the change locally on my machine I want to keep them around, if I push what I have currently a build process will install from the registry which doesn’t have the fix.

I need to tell patch-package what package I want to patch:

yarn patch-package victormono

Then patch-package will create a patches folder in the root of my project where I can inspect the patch changes.

  └─ patches/
    └─ victormono+1.3.1.patch

View the patch

Opening the .patch file displays the changes made:

diff --git a/node_modules/victormono/dist/index.css b/node_modules/victormono/dist/index.css
index 82c84f1..9e1131f 100644
--- a/node_modules/victormono/dist/index.css
+++ b/node_modules/victormono/dist/index.css
@@ -4,6 +4,7 @@
        url("woff/VictorMono-Regular.woff") format("woff");
   font-weight: 400;
   font-style: normal;
+  font-display: swap;

 @font-face {
@@ -12,6 +13,7 @@
        url("woff/VictorMono-Italic.woff") format("woff");
   font-weight: 400;
   font-style: italic;
+  font-display: swap;

 @font-face {
@@ -20,6 +22,7 @@
        url("woff/VictorMono-Bold.woff") format("woff");
   font-weight: 700;
   font-style: normal;
+  font-display: swap;

 @font-face {
@@ -28,4 +31,5 @@
        url("woff/VictorMono-BoldItalic.woff") format("woff");
   font-weight: 700;
   font-style: italic;
+  font-display: swap;
 No newline at end of file

If you have Prettier installed and set to format on save use Ctrl+Shit+p and select File: Save without Formatting when changing other packages

Saving without formatting on the package you want to change will make the .patch file less noisy only including the relevant changes.

Use postinstall

I’ve added postinstall-postinstall to run patch-package, this will mean that the patch file created by patch-package gets applied after the project is built.

"scripts": {
  "postinstall": "patch-package"

I can now publish my project with the patches until the Victor Mono npm package changes. At that time I will get a prompt to tell me the package has changed probably via a failed build, then I can either change my patch or remove it completely.

There's a reactions leaderboard you can check out too.

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