fx

fx

A non-interactive, JavaScript version of the fx. Short for Function eXecution or f(x).

npm i -g fx

Or use npx:

cat file.json | npx fx .field

Or use node:

cat file.json | node <(curl -s https://fx.wtf) .field

Or use deno:

cat file.json | deno run https://fx.wtf .field

Usage

Fx treats arguments as JavaScript functions. Fx passes the input data to the first function and then passes the result of the first function to the second function and so on.

echo '{"name": "world"}' | fx 'x => x.name' 'x => `Hello, ${x}!`'

Use this to access the input data. Use . at the start of the expression to access the input data without a x => x part.

echo '{"name": "world"}' | fx '.name' '`Hello, ${this}!`'

Use other JS functions to process the data.

echo '{"name": "world"}' | fx 'Object.keys'

Advanced Usage

Fx can process a stream of json objects. Fx will apply arguments to each object.

echo '{"name": "hello"}\n{"name": "world"}' | fx '.name'

If you want to process a stream of json objects as a single array, use the --slurp or -s flag.

echo '{"name": "hello"}\n{"name": "world"}' | fx --slurp '.map(x => x.name)' '.join(", ")'

If you want to process non-JSON data, use the --raw or -r flag.

ls | fx -r '[this, this.includes(".md")]'

You can use --raw and --slurp (or -rs) together to get a single array of strings.

ls | fx -rs '.filter(x => x.includes(".md"))'

Fx has a special symbol skip for skipping the printing of the result.

ls | fx -r '.includes(".md") ? this : skip'

Fx comes with a set of useful functions: uniq, sort, groupBy.

cat file.json | fx 'uniq' 'sort' 'groupBy(x => x.name)'

Fx works with promises.

echo '"https://medv.io/*"' | fx 'fetch' '.text()'

Syntactic Sugar

Fx has a shortcut for the map function. Fox example, this.map(x => x.commit.message) can be rewritten without leading dot and without x => x parts.

curl https://api.github.com/repos/antonmedv/fx/commits | fx 'map(.commit.message)'

echo '[{"name": "world"}]' | fx 'map(`Hello, ${x.name}!`)'

Fx has a special syntax for the flatMap function. Fox example, .flatMap(x => x.labels.flatMap(x => x.name)) can be rewritten in the next way.

curl https://api.github.com/repos/kubernetes/kubernetes/issues | fx '.[].labels[].name'

License

MIT