将自定义变量从 npm 脚本设置为 javascript

Question

Might be a duplicate but is there a way to set variables from an npm script that are accessible in javascript via something like process.env.CUSTOM_VAR ?

In my package.json in the scripts section I've added "start": "react-native start --reset-cache" which works fine but now I'd like to do something like this "inspect": "INSPECT=1 react-native start --reset-cache" and have it accessible in javascript. I've googled around everything seems to point to adding it like above but it doesn't seem to be working.

Any help is appreciated!

Answer 1

You can have a program to read the process.argv and do things based on that list(process.argv includes the flags that the script started on)

argvToEnv.js

//you can set the prefix to your liking
const prefix="*" //the start script may have many flags
//if any flag starts with a prefix, it will turn it into an env variable
let envList={} //soon to be list of things env variables
for(let i=0;i<process.argv.length;i++){
  let flag=process.argv[i]
  if(flag.startsWith(prefix)){
    envList[process.argv[i++].substr(prefix.length)]=process.argv[i]
  }
}
Object.keys(envList).forEach(key=>{
  process.env[key]=envList[key]
})

index.js

require('path/to/argvToEnv.js')
//whatever else you do in your main js file

start script

"start": "react-native start --reset-cache *CUSTOM_VAR \"success hehe\""