forked from Archives/fx
142 lines
2.7 KiB
Markdown
142 lines
2.7 KiB
Markdown
<img src="https://user-images.githubusercontent.com/141232/35405308-4b41f446-0238-11e8-86c1-21f407cc8460.png" height="100" alt="fx">
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# [](https://travis-ci.org/antonmedv/fx)
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Command-line JSON processing tool
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## Features
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* Don't need to learn new syntax
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* Plain JavaScript
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* Formatting and highlighting
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## Install
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```
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$ npm install -g fx
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```
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## Usage
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Pipe into `fx` any JSON and anonymous function for reducing it.
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```
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$ fx [code ...]
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```
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Pretty print JSON without passing any arguments:
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```
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$ echo '{"key":"value"}' | fx
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{
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"key": "value"
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}
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```
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### Anonymous function
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Use an anonymous function as reducer which gets JSON and processes it:
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```
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$ echo '{"foo": [{"bar": "value"}]}' | fx 'x => x.foo[0].bar'
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"value"
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```
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### This Binding
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If you don't pass anonymous function `param => ...`, code will be automatically transformed into anonymous function.
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And you can get access to JSON by `this` keyword:
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```
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$ echo '{"foo": [{"bar": "value"}]}' | fx 'this.foo[0].bar'
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"value"
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```
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### Chain
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You can pass any number of anonymous functions for reducing JSON:
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```
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$ echo '{"foo": [{"bar": "value"}]}' | fx 'x => x.foo' 'this[0]' 'this.bar'
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"value"
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```
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### Generator
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If passed code contains `yield` keyword, [generator expression](https://github.com/sebmarkbage/ecmascript-generator-expression)
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will be used:
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```
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$ curl ... | fx 'for (let user of this) if (user.login.startsWith("a")) yield user'
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```
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Access to JSON through `this` keyword:
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```
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$ echo '["a", "b"]' | fx 'yield* this'
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[
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"a",
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"b"
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]
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```
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```
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$ echo '["a", "b"]' | fx 'yield* this; yield "c";'
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[
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"a",
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"b",
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"c"
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]
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```
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### Update
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You can update existing JSON using spread operator:
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```
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$ echo '{"count": 0}' | fx '{...this, count: 1}'
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{
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"count": 1
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}
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```
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### Use npm package
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Use any npm package by installing it globally:
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```
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$ npm install -g lodash
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$ cat package.json | fx 'require("lodash").keys(this.dependencies)'
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```
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### Formatting
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If you need something different then JSON (for example arguments for xargs) do not return anything from reducer.
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Undefined value printed into stderr by default.
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```
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echo '[]' | fx 'void 0'
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undefined
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```
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```
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echo '[1,2,3]' | fx 'this.forEach(x => console.log(x))' 2>/dev/null | xargs echo
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1 2 3
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```
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### Other examples
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Convert object to array:
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```
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$ cat package.json | fx 'Object.keys(this.dependencies)'
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[
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"cardinal",
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"get-stdin",
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"meow"
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]
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```
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## Related
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* [jq](https://github.com/stedolan/jq) – cli JSON processor on C
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* [jsawk](https://github.com/micha/jsawk) – like awk, but for JSON
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* [json](https://github.com/trentm/json) – another JSON manipulating cli library
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* [jl](https://github.com/chrisdone/jl) – functional sed for JSON on Haskell
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## License
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MIT
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