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This is a playground to test code. It runs a full Node.js environment and already has all of npm’s 1,000,000+ packages pre-installed, including es6-lenses. Try it out:
// Important: this example requires ES6 support.
// Looking for typed examples? Open flow-or-typescript-example.ts
const assert = require('assert');
const {_, lens} = require("es6-lenses")
const obj = {x: {y: 1}, z: 2}
// Typed (Flow / TypeScript) alternative:
// lens((_: typeof obj) => _.x.y)
const xy = lens(_.x.y)
// Typed (Flow / TypeScript) alternative:
// lens((_: typeof obj) => [_.x.y, _.z])
const yz = lens([_.x.y, _.z])
// Direct call (~ get)
assert.deepEqual(xy(obj), 1)
assert.deepEqual(yz(obj), [1, 2])
// Get
assert.deepEqual(xy.get(obj), 1)
assert.deepEqual(yz.get(obj), [1, 2])
// Set
assert.deepEqual(xy.set(obj, 10), {x: {y: 10}, z: 2})
assert.deepEqual(yz.set(obj, [11, 22]), {x: {y: 11}, z: 22})
// Set from scratch
assert.deepEqual(xy.set({}, -1), {x: {y: -1}})
assert.deepEqual(yz.set({}, [-1, -2]), {x: {y: -1}, z: -2})
// Mutate
assert.strictEqual(xy.mutate(obj, 666), obj)
assert.deepEqual(obj, {x: {y: 666}, z: 2})
assert.strictEqual(yz.mutate(obj, [111, 222]), obj)
assert.deepEqual(obj, {x: {y: 111}, z: 222})
console.log('OK!')
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