Selectors

Immutable JSON selectors.

A small lib that help manipulating JSON objects in an immutable way.

Example

``js
'use strict';

var selectors = require('selectors')
, lift = selectors.liftSelection
, map = selectors.mapSelection
, select = selectors.select
, has = selectors.hasSelection
, set = selectors.setSelection
;


var obj = {
a: {
b: 100
}
}

// Has with a path selector
console.log("Has obj.a.b?", has(['a','b'], obj))
// Result: Has obj.a.b? true

// Has with a prop selector
console.log("Has obj.Z?", has('A', obj));
// Has obj.Z? false

// Select with a path selector
console.log("obj.a.b: ", select(['a', 'b'], obj));
// obj.a.b: 100

// Select with a prop selector
console.log("obj.a: ", select('a', obj));
// obj.a: { b: 100 }

// Set a new selected property
var immutable = set(['a','c'], "I am new", obj);
console.log("New:", immutable, "Old:", obj);
// New: { a: { b: 100, c: 'I am new' } } Old: { a: { b: 100 } }

// Create a new object
console.log("New object: ", set(['x', 'y', 'z'], "I was just created", {}));
// New object: { x: { y: { z: 'I was just created' } } }

// Create a new object from undefined
console.log("From undefined: ", set(['create', 'from', 'undefined'], "CHECK")());
// From undefined: { create: { from: { undefined: 'CHECK' } } }

// Lift example
function add(x, y) {return x+y;}
var addTen = add.bind(null, 10);
console.log('obj.a.b + 10:', lift(addTen, ['a', 'b'], obj))
// obj.a.b + 10: 110

// Curried lift
function mul(x, y) {return x*y;}
var mulSelectionByEleven = lift(mul.bind(null, 11));
console.log('obj.a.b * 11:', mulSelectionByEleven(['a', 'b'], obj))
// obj.a.b * 11: 1100

// Curried map example
var incrementSelection = map(add.bind(null,1));
var incremented = incrementSelection(['a', 'b'], obj);
console.log('Original:', obj, 'Incremented:',incremented);
// Original: { a: { b: 100 } } Incremented: { a: { b: 101 } }
`

methods

`js
var selectors = require('selectors');
`

All methods are auto curried and can be composed to new functions.

Common Attributes:

* selector - Several variations might apply
* string - Selects the property
* array - Selects a path
* Undefined|[] - Selects the whole object
* obj - The JSON object to select from. It could be an empty object as well as Undefined. When it's undefined
it will simply create a new object.

$3

Returns false if the selector is undefined.

$3

Returns the value of the selection.

$3

Sets a new value for the selection.

Returns a new object with updated value.

$3

f - a function with the signature of f(x).

Lifts/Injects the value of the selection into f.

Returns the value of f(x).

$3

f - a function with a signature of f(x).

Maps the value of the selection with f.

Returns a new object with the value of f(x) at the selection.

install

With npm do:

`
npm install selectors
``

license

MIT