# Documentation

`fx` can work in two modes: as reducer or interactive. 
To start interactive mode pipe any JSON into `fx`:

```sh
$ curl ... | fx
```

Or you can pass a filename as the first parameter:

```sh
$ fx data.json
```

## Reducers

If any additional arguments was passed, fx converts it to a function which takes
JSON as argument named `x`.

By default, fx uses builtin JavaScript VM ([goja](https://github.com/dop251/goja)), 
but fx also can be used with [node](#node), [python](#python), or [ruby](#ruby).

### JavaScript

```sh
FX_LANG=js
```

An example of anonymous function used as reducer:
```sh
$ echo '{"foo": [{"bar": "value"}]}' | fx 'x => x.foo[0].bar'
value
```

The same reducer function can be simplified to:

```sh
$ echo '{"foo": [{"bar": "value"}]}' | fx 'x.foo[0].bar'
value
```

Each argument treated as a reducer function.

```sh
$ echo '{"foo": [{"bar": "value"}]}' | fx 'x.foo' 'x[0]' 'x.bar'
value
```

Update JSON using the spread operator:

```sh
$ echo '{"name": "fx", "count": 0}' | fx '{...this, count: 1}'
{
  "name": "fx",
  "count": 1
}
```

### Dot

Fx supports simple JS-like syntax for accessing data, which can be used with any
`FX_LANG`.

```sh
$ echo '{"foo": [{"bar": "value"}]}' | fx .foo[0].bar
value
```

### .fxrc.js

Create _.fxrc.js_ file in `$HOME` directory, and define some useful functions.

```js
// .fxrc.js
function upper(s) {
  return s.toUpperCase()
}
```

```sh
$ cat data.json | fx .name upper
ANTON
```

### Node

```sh
FX_LANG=node
```

### Npm packages

Use any npm package by installing it globally. Create _.fxrc.js_ file in `$HOME` 
directory, and require any packages or define global functions.

For example, access all lodash methods without `_` prefix. 

Put next line your _.fxrc.js_ file:

```js
Object.assign(global, require('lodash/fp'))
```

And now you will be able to call all lodash methods. For example, see who's been committing to react recently:

```sh
curl 'https://api.github.com/repos/facebook/react/commits?per_page=100' \
| fx 'groupBy("commit.author.name")' 'mapValues(size)' toPairs 'sortBy(1)' reverse 'take(10)' fromPairs
```

> To be able to require global modules make sure you have correct `NODE_PATH` env variable.
> ```sh
> export NODE_PATH=`npm root -g`
> ```

The _.fxrc.js_ file supports both: import and require.

```js
import 'zx/globals'
const _ = require('lodash')
```

> With you want to use _.fxrc.js_ for both `FX_LANG=js` and `FX_LANG=node`,
> separate parts by `// nodejs:` comment:
> ```js
> function upper(s) {
>   return s.toUpperCase()
> }
> // nodejs:
> import 'zx/globals'
> const _ = require('lodash')
> ```

### Python

```sh
FX_LANG=python
```
Or 
```sh
FX_LANG=python3
```

Example:

```sh
fx data.json '[x["age"] + i for i in range(10)]'
```

### Ruby

```sh
FX_LANG=ruby
```

Example:

```sh
fx data.json 'x.to_a.map {|x| x[1]}'
```

## Streaming mode

`fx` supports line-delimited JSON streaming and concatenated JSON streaming.

```sh
$ kubectl logs ... | fx .message
```

## Interactive mode

Type `?` to see full list of available shortcuts while in interactive mode.

### Search

Press `/` and type regexp pattern to search in current JSON. 
Search is performed on internal representation of the JSON without newlines.

Type `n` to jump to next result, and `N` to previous.s

### Selecting text

You can't just select text in fx. This is due the fact that all mouse events are 
redirected to stdin. To be able to 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         |