Automatic npm install --legacy-peer-deps for a single dependency - npm

Question

Assume I have a package.json like this:
{
"name": "my-app",
"version": "0.1.0",
"dependencies": {
"#aws-sdk/client-s3": "^3.21.0",
"#testing-library/react": "^11.2.5",
"axios": "^0.22.0",
"credit-card-type": "^8.3.0",
"csstype": "^3.0.8",
"dayjs": "^1.10.4",
"lodash": "^4.17.20",
"mathjax-full": "^3.2.0",
"mathjax-react": "^1.0.6",
"react": "^17.0.2",
},
"proxy": "http://localhost:5000",
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "jest",
"eject": "react-scripts eject",
},
"browserslist": {
"production": [
">0.2%",
"not dead",
"not op_mini all"
],
"development": [
"last 1 chrome version",
"last 1 firefox version",
"last 1 safari version"
]
}
}
The problem is that the dependency mathjax-react & mathjax-full need react#"^15.0.0 || ^16.0.0". I have tested with npm i --force and npm i --legacy-peer-deps and It all seems to work fine with my react version which is react#17.0.2.
I wouldn't like to run npm i --force and npm i --legacy-peer-deps every time i need to install the dependencies, So I was looking for a way to automatically do that only for the mathjax-react & mathjax-full whenever I run npm i. I tried looking in the .npmrc docs and this reference, but could not find a way to do that. What might be a solution for this? Is there a native npm solution for this? Or do i have to write a script that reads my package.json and runs npm install for every dependency alone?
My reasoning is that if i need to install some other dependencies that have conflicts, I'd never be warned about it.

Answer 1

Legacy peer dependencies aren't per-package, they apply to the project as a whole. It's just that you might need it for your whole project to keep only one or two dependencies happy. You'll find if you install a package with --legacy-peer-deps and then install a different package without that flag, npm will complain about the first package again. So once you need --legacy-peer-deps, you need to specify it always no matter what package you install.
According to the docs, you can set it permanently with:
npm config set legacy-peer-deps=true --location=project
This just adds legacy-peer-deps=true to the end of the .npmrc in your project root.