How to fetch package version and date in npm script?

Question

I have a package.json file and I have this script to create 2 separate files one for version and other one for date.

When i run the command, it generates the version-npm.txt with correct data holding the current version, but the version.txt file is generated with the exact script instead, it contains date +"%d/%m/%Y %T"

"scripts": {
    "versions": "node -e \"console.log(require('./package.json').version);\" > ./public/version-npm.txt && echo `date +\"%d/%m/%Y %T\"` > ./public/version.txt" 
}

I need this to be updated with the current date and time. is there any other way to it or can you help me fix it?

i tried writing the date as \"$(date)\" still the same, now i get \"$(date)\"

score 2 · Accepted Answer · edited Jun 20 '20 at 09:12

Why is it not working?

The way that you are obtaining the date, i.e. date +\"%d/%m/%Y %T\" or similarly using \"$(date)\" does work successfully on *nix platforms, whereby npm utilizes sh by default to run npm scripts.
However, the aforementioned method does not work on Windows because npm on that OS utilizes cmd as the default shell to run npm scripts - cmd simply does not understand the date command.

Solution

The following solution will work cross-platforms (Windows, Linux, MacOS etc) :

Firstly cd to your project directory and install the moment package by running the following command:
```
npm i -D moment
```
We'll utilize this package to obtain the date/time formatted as DD/MM/YYY HH:MM:SS.

Then redefine your versions script in the scripts section of your package.json as follows:

"scripts": {
  "versions": "node -p \"process.env.npm_package_version\" > ./public/version-npm.txt && node -p \"require('moment')().format('MM/DD/YYYY HH:mm:ss')\" > ./public/version.txt"
}

Explanation:

The npm script (above) utilizes the nodejs command line option -p to evaluate and print the result of the following inline JavaScript:
```
process.env.npm_package_version
```
This essentially utilizes nodejs process.env to read the environment variable npm_package_version which npm creates. See my answer here for further explanation.

The version is then redirected (>) to the file using the same method as per your attempt:
```
> ./public/version-npm.txt
```
Note: You could continue to utilize your current, more verbose, solution to obtain the version from package.json if you prefer, i.e.
```
node -e \"console.log(require('./package.json').version);\"
```
Next we obtain the date. Again we utilize the nodejs command line option -p to evaluate and print the result of the following inline JavaScript:
```
require('moment')().format('MM/DD/YYYY HH:mm:ss')
```
The date value is redirected (>) to the file as follows:
```
> ./public/version.txt
```

**Note:** If your are using an early version of node.js then you may encounter errors with `moment`. In which case install an earlier version. For example run `npm i -D moment@1.7.2` instead of `npm i -D moment` — RobC, Jun 03 '20 at 15:26

How to fetch package version and date in npm script?

1 Answers1

Why is it not working?

Solution