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README.md
* Function eXecution
Command-line JSON processing tool
Features
- Don't need to learn new syntax
- Plain JavaScript
- Formatting and highlighting
- Standalone binary
- Interactive mode 🎉
Install
$ npm install -g fx
Or via Homebrew
$ brew install fx
Or download standalone binary from releases page.
Usage
Pipe into fx
any JSON and anonymous function for reducing it.
$ echo '{...}' | fx [code ...]
Start interactive mode without passing any arguments:
$ curl ... | fx
Anonymous function
Use an anonymous function as reducer which gets JSON and processes it:
$ echo '{"foo": [{"bar": "value"}]}' | fx 'x => x.foo[0].bar'
value
Binding
If you don't pass anonymous function param => ...
, code will be automatically transformed into anonymous function.
And you can get access to JSON by this
keyword:
$ echo '{"foo": [{"bar": "value"}]}' | fx 'this.foo[0].bar'
value
Dot
It is possible to omit this
keyword:
$ echo '{"foo": [{"bar": "value"}]}' | fx .foo[0].bar
value
If single dot is passed, JSON will be processed without modification:
$ echo '{"foo": "bar"}' | fx .
{
"foo": "bar"
}
Chain
You can pass any number of anonymous functions for reducing JSON:
$ echo '{"foo": [{"bar": "value"}]}' | fx 'x => x.foo' 'this[0]' 'this.bar'
value
Generator
If passed code contains yield
keyword, generator expression
will be used:
$ curl ... | fx 'for (let user of this) if (user.login.startsWith("a")) yield user'
Access to JSON through this
keyword:
$ echo '["a", "b"]' | fx 'yield* this'
[
"a",
"b"
]
$ echo '["a", "b"]' | fx 'yield* this; yield "c";'
[
"a",
"b",
"c"
]
Update
You can update existing JSON using spread operator:
$ echo '{"count": 0}' | fx '{...this, count: 1}'
{
"count": 1
}
Using packages
Use any npm package by installing it globally:
$ npm install -g lodash
$ cat package.json | fx 'require("lodash").keys(this.dependencies)'
Using .fxrc
Create .fxrc file in $HOME
directory, and require any packages or define global functions.
For example, access all lodash methods without _
prefix. Put in your .fxrc
file:
Object.assign(global, require('lodash'))
And now you will be able to call all lodash methods. For example, see who's been committing to react recently:
curl 'https://api.github.com/repos/facebook/react/commits?per_page=100' \
| fx 'mapValues(groupBy(this, "commit.committer.name"), size)'
To be able require global modules make sure you have correct
NODE_PATH
env variable.export NODE_PATH=/usr/local/lib/node_modules
Formatting
If you need something different then JSON (for example arguments for xargs) do not return anything from reducer.
undefined
value is printed into stderr by default.
echo '[]' | fx 'void 0'
undefined
echo '[1,2,3]' | fx 'this.forEach(x => console.log(x))' 2>/dev/null | xargs echo
1 2 3
Other examples
Convert object to array:
$ cat package.json | fx 'Object.keys(this.dependencies)'
[
"@medv/prettyjson"
]
By the way, fx has shortcut for Object.keys(this)
. Previous example can be rewritten as:
$ cat package.json | fx this.dependencies ?
Interactive mode
Start interactive mode without passing any arguments:
$ curl ... | fx
Click on fields to expand or collapse JSON tree, use mouse wheel to scroll view.
Next commands available in interactive mode:
Key | Command |
---|---|
q or Esc or Ctrl +c |
Exit |
e /E |
Expand/Collapse all |
up /down or k /j |
Scroll up/down one line |
g /G |
Goto top/bottom |
Selecting text
You may found what you can't just select text in fx. This is due the fact that all mouse events redirected to stdin. To be able select again you need instruct your terminal not to do it. This can be done by holding special keys while selecting:
Key | Terminal |
---|---|
Option +Mouse |
iTerm2, Hyper |
Fn +Mouse |
Terminal.app |
Shift +Mouse |
Linux |