Configure repository field on package.json on monorepo - node.js

Question

Situation
I have a monorepo created with lerna with 40-50 projects. Each has a package.json like this.
{
"name": "#base-repo/add-class-methods",
"version": "1.0.0",
"main": "index.js",
"license": "MIT"
}
The folder structure is like this,
packages
├── absolute-url
│ ├── index.js
│ └── package.json
├── add-class-methods
│ ├── index.js
│ └── package.json
├── check-set-relative
│ ├── index.js
│ └── package.json
├── crypto
│ ├── index.js
│ └── package.json
If I push it to github, it will have a single github url, however I saw babel has 142 packages where each of them has a custom repository field in the package.json.
"repository": "https://github.com/babel/babel/tree/master/packages/babel-types"
I hope they are not setting this value manually for 142 packages. Same with my 40 small packages.
I understand I can manually set them in 3-4 minutes by the time I am writing this question. However this will get overwhelming when I try to do the same with a 150 package monorepo or in future.
Problem
How can I set/update the repository field without opening each package.json file manually for 40 packages?
What I tried
Manually set each as possible, but things quickly got boring and repeating considering I am a programmer. Then I googled the solution for around an hour. Finally I wrote the following script,
const glob = require('glob');
const fs = require('fs');
const path = require('path');
const gitUrl = 'https://github.com/user';
const author = `Mr. Github User <user#example.com> (${gitUrl})`;
const basePath = '/utility-scripts/tree/master';
const baseRepo = gitUrl + basePath;
glob('packages/*/package.json', (err, files) => {
for (const filePath of files) {
const [parent, pkg] = filePath.split('/');
const newData = {
author,
license: 'MIT',
repository: `${baseRepo}/${parent}/${pkg}`,
};
const data = Object.assign(
{},
JSON.parse(fs.readFileSync(path.resolve(filePath), 'utf-8')),
newData,
);
fs.writeFileSync(path.resolve(filePath), JSON.stringify(data, true, 2));
}
});
Is there an easy way to deal with this? With any kind of shell, git, yarn or npm command?