\n\n\n\n- [Install](#install)\n- [Getting Started](#getting-started)\n- [Docs](#docs)\n- [Migration](#migration)\n- [API](#api)\n - [of](#of)\n - [isJust](#isjust)\n - [isNothing](#isnothing)\n - [join](#join)\n - [orElse](#orelse)\n - [map](#mapfunc)\n - [chain](#chainfunc)\n- [Credit](#credit)\n\n## Install\n\n* `npm install --save maybe-baby`\n* `yarn add maybe-baby`\n\n---\n\n## Getting Started\n\nWhat if we need the `zipCode` of the user below, which lives on the `address` object? \n\n```javascript\nconst user = { \n email: 'foo@bar.com',\n address: null,\n name: {\n first: 'John',\n last: null,\n middle: null\n }\n};\n```\n\nAccessing it via dot notation will result in an error: \n\n```javascript\nconst zipCode = user.address.zipCode; // Uncaught TypeError: Cannot read property 'zipCode' of undefined\n```\n\n### Possible Solutions?\n\n1. Write some ugly null checks that don't scale well:\n\n```javascript\nconst getZipCode = (user) => {\n if (user !== null && user !== undefined) {\n if (user.address !== null && user.address !== undefined) {\n return user.address.zipCode\n }\n }\n}\n```\n\n2. Use [`_.get()`](https://lodash.com/docs/4.17.4#get) or something similar, but these libraries have large footprints, and most likely won't be implementing the monadic structure.\n\n3. Wait for [optional chaining](https://github.com/tc39/proposal-optional-chaining) to be approved in ECMA, or use [babel-plugin-transform-optional-chaining](https://www.npmjs.com/package/babel-plugin-transform-optional-chaining).\n\n4. Use TypeScript's [optional chaining](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html) \n\n### A Better Solution?\n\n1. Use `maybe-baby` to minimize defensive coding:\n\n```javascript\nimport Maybe from 'maybe-baby';\n\n// Use a function getter\nconst getZipCode = (user) => Maybe.of(() => user.address.zipCode).join();\n\n```\n\nNow we can safely get the `zipCode` without worrying about the shape of the object, or encountering `TypeErrors`:\n\n```js\nconst zipCode = getZipCode(user);\nconsole.log(zipCode); // undefined\n```\n\n----\n\n## Docs\n\nDocumentation generated via [JSDoc](https://github.com/jsdoc3/jsdoc).\n\n* [https://mikechabot.github.io/maybe-baby/](https://mikechabot.github.io/maybe-baby/)\n\n---\n\n## Migrating from 1.x to 2.x\n\nBreaking changes were introduced in 2.0.0; the following redundant function were removed.\n\n> Maybe.of() can replicate the behavior of `prop`, `props`, and `path`.\n\n### `prop(val: string | number)`\n\n```javascript\nconst obj = Maybe.of({ \n foo: { \n bar: [123, 456] \n } \n});\n\n// Incorrect\nconst bar = obj.prop(\"foo\").join(); // { bar: [123, 456] }\n\n// Correct\nMaybe.of(() => obj.join().foo).join(); // { bar: [123, 456] }\n\n// Incorrect\nobj\n .prop(\"foo\")\n .prop(\"bar\")\n .prop(1)\n .join(); // 456\n\n// Correct\nMaybe.of(() => obj.join().foo.bar[1]).join() // 456\n```\n\n### `props(...args)`\n\n```javascript\nconst obj = Maybe.of({\n foo: 'bar',\n baz: [1,2,3]\n});\n\n// Incorrect\nobj.props('baz', 0).join(); // 1\n\n// Correct\nMaybe.of(() => obj.join().baz[0]).join(); // 1\n```\n\n### `props(val: string)`\n\n```javascript\nconst obj = Maybe.of({\n foo: 'bar',\n baz: [1,2,3]\n});\n\n// Incorrect\nobj.path('baz.0').join() // 1\n\n// Correct\nMaybe.of(() => obj.join().baz[0]).join(); // 1\n```\n\n---\n\n## API\n\nCheck out the API below, or the complete [documentation](https://mikechabot.github.io/maybe-baby/).\n\n### `of(val: unknown | OfTypeFunc)`\n\nAccepts a value of any type, and returns a monad:\n\n```javascript\nconst str = Maybe.of('foo');\nconst num = Maybe.of(123);\nconst bool = Maybe.of(true);\nconst obj = Maybe.of({});\nconst arr = Maybe.of([]);\nconst empty = Maybe.of(null);\nconst undef = Maybe.of(undefined);\n```\n\nAccepts a function, and sets the function's return value as the monad's value, returns a monad. \n\n> If the function results in an error, the monad's value is set to `undefined`.\n\n```typescript\ntype OfTypeFunc = () => T;\n\nconst user = {};\nconst mZipCode = Maybe.of(() => user.address.zipCode);\n\nconsole.log(mZipCode.join()); // undefined\n```\n----\n\n### `isJust(): boolean`\n\nReturns `true` if the value is not `null` or `undefined`:\n\n```javascript\nMaybe.of(123).isJust(); // true\nMaybe.of(null).isJust(); // false\n```\n\n----\n\n### `isNothing(): boolean`\n\nReturns `true` if the value is `null` or `undefined`:\n\n```javascript\nMaybe.of(123).isNothing(); // false\nMaybe.of(null).isNothing(); // true\n```\n----\n\n### `join(): T`\n\nReturns the value:\n\n```javascript\nMaybe.of(123).join(); // 123\nMaybe.of(null).join(); // null\n```\n\n----\n\n### `orElse(defaultValue: unknown): Maybe`\n\nChain to the end of a monad to return as the default value if `isNothing()` is `true`:\n\n```javascript\nMaybe.of(undefined)\n .orElse('No Value')\n .join(); // 'No Value'\n```\n\n----\n\n### `map(transform: (val: T) => T | Maybe): Maybe`\n\nApply a transformation to the monad, and return a new monad:\n\n```javascript\nconst val = 1;\nconst newVal = Maybe.of(val).map(val => val + 1);\n\nnewVal.join(); // 2;\n```\n\n----\n\n### `chain(chain: (val: T) => Maybe): Maybe`\n\nChain together functions that return Maybe monads:\n\n```javascript\nfunction addOne (val) {\n return Maybe.of(val + 1);\n}\n\nconst three = Maybe.of(1)\n .chain(addOne)\n .chain(addOne);\n\n three.join(); // 3\n```\n\n----\n\n## Credit\n\nCredit to [James Sinclair](https://github.com/jrsinclair) for writing [The Marvellously Mysterious JavaScript Maybe Monad](http://jrsinclair.com/articles/2016/marvellously-mysterious-javascript-maybe-monad/).\n","maintainers":[{"name":"mikechabot","email":"mike.chabot@live.com"}],"time":{"modified":"2022-06-19T17:01:33.040Z","created":"2016-12-19T17:04:09.334Z","0.0.1":"2016-12-19T17:04:09.334Z","0.0.2":"2016-12-19T17:12:12.223Z","0.0.3":"2016-12-19T17:13:04.857Z","0.0.4":"2016-12-30T00:20:17.109Z","0.0.5":"2016-12-30T00:32:50.028Z","0.0.6":"2016-12-30T00:56:48.939Z","0.0.7":"2017-01-31T15:56:33.854Z","0.0.8":"2017-01-31T15:58:11.889Z","0.0.9":"2017-06-10T18:02:20.656Z","0.1.0":"2017-08-04T15:56:27.746Z","1.0.1":"2017-09-16T06:26:23.619Z","1.0.2":"2017-09-16T06:35:39.833Z","1.0.3":"2017-09-16T16:10:54.053Z","1.0.4":"2017-09-16T16:40:15.251Z","1.0.5":"2017-09-17T03:02:38.271Z","1.0.7":"2017-09-18T15:53:42.268Z","1.0.9":"2017-09-20T03:39:32.432Z","1.0.10":"2017-09-20T03:51:13.192Z","1.0.12":"2017-09-20T14:41:12.076Z","1.0.13":"2017-09-21T17:20:33.075Z","1.0.16":"2017-09-21T21:33:59.054Z","1.0.18":"2017-09-22T01:44:08.284Z","1.0.19":"2017-09-22T02:35:55.823Z","1.0.20":"2017-11-13T16:14:45.981Z","1.0.22":"2018-05-23T16:36:20.087Z","1.0.23":"2018-05-24T17:30:07.711Z","1.0.24":"2018-05-24T18:04:08.116Z","1.1.0":"2018-07-12T19:05:21.072Z","1.1.2":"2018-07-12T20:20:47.204Z","1.1.4":"2018-07-12T20:24:33.922Z","1.1.5":"2018-07-13T20:51:21.507Z","1.1.6":"2018-07-13T20:59:14.772Z","1.1.7":"2018-11-17T21:02:45.701Z","1.1.8":"2018-11-18T19:05:39.074Z","1.1.10":"2019-04-27T16:16:58.804Z","2.0.0-beta.0":"2020-12-21T06:11:17.794Z","2.0.0-beta.1":"2020-12-21T06:14:21.833Z","2.0.0":"2020-12-21T07:10:22.818Z","2.0.1":"2020-12-21T07:11:54.868Z","2.0.3":"2020-12-21T07:21:40.861Z"},"homepage":"https://github.com/mikechabot/maybe-baby#readme","keywords":["maybe","monad","javascript"],"repository":{"type":"git","url":"git+https://github.com/mikechabot/maybe-baby.git"},"author":{"name":"Mike Chabot"},"bugs":{"url":"https://github.com/mikechabot/maybe-baby/issues"},"license":"MIT","readmeFilename":"README.md","users":{"mikechabot":true}}
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