# [](https://travis-ci.org/antonmedv/fx) Command-line JSON processing tool ## Features * Don't need to learn new syntax * Plain JavaScript * Formatting and highlighting * Standalone binary ## Install ``` $ npm install -g fx ``` Or download standalone binary from [releases](https://github.com/antonmedv/fx/releases) page. ## Usage Pipe into `fx` any JSON and anonymous function for reducing it. ``` $ fx [code ...] ``` Pretty print JSON without passing any arguments: ``` $ echo '{"key":"value"}' | fx { "key": "value" } ``` ### 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 ``` ### This 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 ``` ### 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](https://github.com/sebmarkbage/ecmascript-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 } ``` ### Use npm package Use any npm package by installing it globally: ``` $ npm install -g lodash $ cat package.json | fx 'require("lodash").keys(this.dependencies)' ``` ### Formatting If you need something different then JSON (for example arguments for xargs) do not return anything from reducer. `undefined` value 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", "get-stdin", "meow" ] ``` By the way, fx has shortcut for `Object.keys(this)`. Previous example can be rewritten as: ``` $ cat package.json | fx this.dependencies ? ``` ## Related * [jq](https://github.com/stedolan/jq) – cli JSON processor on C * [jl](https://github.com/chrisdone/jl) – functional sed for JSON on Haskell * [xx](https://github.com/antonmedv/xx) – `fx`-like JSON tool on Go * [ymlx](https://github.com/matthewadams/ymlx) - `fx`-like YAML cli processor ## License MIT