How to patch node_module source code

Credits:

• https://stackoverflow.com/questions/72820625/what-is-the-proper-way-to-patch-a-node-modules-module

Install all your dependencies, make sure /node_modules is properly installed:

npm ci

Install patche-packages and postinstall dependencies:

npm install patch-package postinstall-postinstall

Modify package.json to automatically apply patches after install:

{
  // ...
  "scripts": {
    // ...
    "postinstall": "patch-package"
  }

  // ...
}

Modify code in /node_modules, e.g., Changing highlight.js source code as below:

// before the change
regex: {
    concat: (...args: (RegExp | string)[]) => string,
    lookahead: (re: RegExp | string) => string,
    either: (...args: (RegExp | string)[] | any) => string,
    optional: (re: RegExp | string) => string,
    anyNumberOfTimes: (re: RegExp | string) => string
}
newInstance: () => HLJSApi

// after the change
regex: {
    concat: (...args: (RegExp | string)[]) => string,
    lookahead: (re: RegExp | string) => string,
    either: (...args: (RegExp | string)[] | any) => string, // <<<<<<<< Change this
    optional: (re: RegExp | string) => string,
    anyNumberOfTimes: (re: RegExp | string) => string
}
newInstance: () => HLJSApi

Create patch using npx:

npx patch-package highlight.js

Patch file is created at /patches folder, it looks this:

Filename: highlight.js+11.9.0.patch

diff --git a/node_modules/highlight.js/types/index.d.ts b/node_modules/highlight.js/types/index.d.ts
index 1941e61..8b4d959 100644
--- a/node_modules/highlight.js/types/index.d.ts
+++ b/node_modules/highlight.js/types/index.d.ts
@@ -53,7 +53,7 @@ declare module 'highlight.js' {
         regex: {
             concat: (...args: (RegExp | string)[]) => string,
             lookahead: (re: RegExp | string) => string,
-            either: (...args: (RegExp | string)[] | [...(RegExp | string)[], RegexEitherOptions]) => string,
+            either: (...args: any) => string, // <<<<<<<< Change this
             optional: (re: RegExp | string) => string,
             anyNumberOfTimes: (re: RegExp | string) => string
         }