How to use package.json scripts to copy files with specific file extension

npm package.json build-tools
Thomas Jørgensen picture Thomas Jørgensen · Jun 25, 2016 · Viewed 82.5k times · Source

I am trying out npm as a build tool.

One stumbling block I have encountered is that I need to copy javascript files from one folder to another. The source folder contains typescript files, javascript files and map files, but in the target folder I am only interested in javascript files.

I do not want to make a copy-statement for each file, but would like to copy all .js files. Also, my source folder contains subfolders that also contains javascript files. These need to be copied as well, and maintain the subfolder structure.

What I have tried is using NCP with a filter, but I cannot get the filter to work. I have tested the regex used in the filter and it appears to work fine. The test was done at Regex Tester with regular expression .*\.js$ and test-strings like main.ts, main.js main.js.map etc, and only the .js strings were matched.

My package json contains the following (abbreviated):

{
    "scripts": {
        "copy": "ncp scripts wwwroot/scripts --filter=\".*(\\\\.js$)\"" 
    }, 
    "devDependencies": { 
        "ncp": "2.0.0.0" 
    }
}

Since my regex is in a string in a string I have double-escaped it. I have also tried other variations, for example:

--filter=/.*\.js$/g       - compilation error
--filter=/.*\\.js$/g      - no files copied
--filter=\".*\\.js$\"     - no files copied
--filter=\"/.*\\.js$/g\"  - no files copied
(no filter)               - all files copied

I am in no way married to NCP. If something else works better then I will use that.

So: How do I, inside package.json's scripts section copy only files with a speific extension to another folder? I am pretty sure I have overlooked something blindingly obvious...

Answer

Matthew Bakaitis picture Matthew Bakaitis · Jun 25, 2016

Warning! The cpx package appears to be abandoned. cpy-cli, copyfiles, and other solutions are listed in comments here or answers, below.

cpx might be a good substitution.

It has a CLI, allows you to use globs instead of regex, can preserve the directory tree, and is relatively up-to-date as I write this....

Related questions

What's the difference between tilde(~) and caret(^) in package.json?

After I upgraded to latest stable node and npm, I tried npm install moment --save. It saves the entry in the package.json with the caret ^ prefix. Previously, it was a tilde ~ prefix. Why are these changes made in npm? …

Read More
What's the difference between dependencies, devDependencies and peerDependencies in npm package.json file?

This documentation answers my question very poorly. I didn't understand those explanations. Can someone say in simpler words? Maybe with examples if it's hard to choose simple words? EDIT also added peerDependencies, which is closely related and might cause confusion.

Read More
How to set environment variables from within package.json

How to set some environment variables from within package.json to be used with npm start like commands? Here's what I currently have in my package.json: { ... "scripts": { "help": "tagove help", "start": "tagove start" } ... } I want to set environment variables (…

Read More