Tiny (220 bytes), zero dependency wrapper for nullable values.
// With nanoption
import { Option } from 'nanoption'
function getJwtToken(executionContext) {
const jwtToken = Option.of(executionContext)
.map(context => context.switchToHttp()) // context can have no http mod (e.g. WebSocket)
.map(httpMod => httpMod.getRequest()) // context can have no http request
.map(request => request.headers) // request can have no headers
.map(headers => headers.authorizarion) // headers can have no auth header
.map(jwtAuth => jwtAuth.split(' ')[1]) // auth header can contain only one part
.getOrElse('')
return jwtToken
}
// Without nanoption
function getJwtToken(executionContext) {
const httpMod = executionContext.switchToHttp()
if (!httpMod) return '' // context can have no http mod (e.g. WebSocket)
const request = httpMod.getRequest()
if (!request) return '' // context can have no http request
const headers = request.headers
if (!headers) return '' // request can have no headers
const jwtAuth = headers.authorizarion
if (!jwtAuth) return '' // headers can have no auth header
const jwtToken = wtAuth.split(' ')[1]
if (!jwtToken) return '' // auth header can contain only one part
return jwtAuth
}yarn add nanoptionOr if you prefer npm:
npm i nanoptionIt JS in some cases we can get an error Cannot do something of undefined/null. This library explicitly works with nullable values and provide clear interface for it.
Also, library support TypeSciript as first-class citizen and do some checks in complie time. For example:
import { Option } from 'nanoption'
// #map
Option.of(2).map(_ => _ * 2) // Some(4)
Option.of().map(() => 2) // None (known at compile time)
// #get
Option.of(3).get() // 3
Option.of().get() // COMPILE ERROR! Can't call get() on NoneOf course, you can use JavaScript without TypeScript, but it's not as fun.
Now Optional Chaining Proposal only on stage 1, but very useful. This library give ECMAScript-version independent alternative for it.
import { Option } from 'nanoption'
// Create an option
Option.of(3) // Some(3)
Option.of('abc') // Some('abc')
Option.of(null) // None
Option.of(undefined) // None
// #map
Option.of(2).map(_ => _ * 2) // Some(4)
Option.of().map(() => 2) // None
// #flatMap
Option.of(3).flatMap(_ => Option.of(_ * 2)) // Some(6)
Option.of().flatMap(() => Option.of(2)) // None
// #get
Option.of(3).get() // 3
Option.of().get() // throw Exception
// #getOrElse
Option.of(1).getOrElse(2) // 1
Option.of(null).getOrElse(2) // 2
// #isEmpty
Option.of(2).isEmpty() // false
Option.of().isEmpty() // true
// #nonEmpty
Option.of(2).nonEmpty() // true
Option.of().nonEmpty() // false
// #toString
Option.of(2).toString() // "Some(2)"
Option.of().toString() // "None"- tsoption is Fantasyland-compliant, but it requires 2-3 times more space.
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