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@ -24,7 +24,7 @@ Pipe into `fx` any JSON and anonymous function for reducing it.
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$ fx [code ...]
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```
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Pretty print JSON:
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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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@ -32,34 +32,42 @@ $ echo '{"key":"value"}' | fx
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}
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```
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Use anonymous function:
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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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$ 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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$ 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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$ 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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$ 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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$ echo '["a", "b"]' | fx 'yield* this'
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[
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"a",
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"b"
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@ -67,7 +75,7 @@ $ echo '["a", "b"]' | fx "yield* this"
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```
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```
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$ echo '["a", "b"]' | fx "yield* this; yield 'c';"
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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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@ -75,18 +83,30 @@ $ echo '["a", "b"]' | fx "yield* this; yield '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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$ 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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### Other examples
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Convert object to array:
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```
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$ cat package.json | fx "yield* Object.keys(this.dependencies)"
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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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@ -94,12 +114,6 @@ $ cat package.json | fx "yield* Object.keys(this.dependencies)"
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]
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```
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Use any npm package:
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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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## Related
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