kenmori

rewiredしたCRAでTypeScirptのパス解決を相対パスから絶対パスに変更した際のnode_modulesまでbaseUrlになる場合の解決

Your project's baseUrl can only be set to src or node_modules. Create React App does not support other values at this time.

To Fix

• Add src/.env
• Add src/path.json

kenmori

Separate optional and required types that can have null types

type NullAbleType<T> = {[K in keyof T]: T[K] | null}
type Option = { money: number, fn: (...arg: any[])=> void}
type User = {name: string, age: number}
type UserWithOPtionNullAble = User & NullAbleType<Partial<Option>>

// const obj:UserWithOPtionNullAble = {name: "kenji", age: 99, money: 222, fn: ()=>{}}

kenmori

Type that has null able and optional, but function type is require.

type NullAbleType<T> = {[K in keyof T]: T[K] | null}
type User = {name: string, age: number, money: null, fn: (...arg: any[])=> void}
type FunctionType<T> = {[K in keyof T]: T[K] extends Function? T[K] : never}[keyof T]
type FunctionName = "fun"
type NullAbleUserAndRequireFunction<T> = NullAbleType<Partial<User>> & {[K in T extends FunctionName ? T: never]: FunctionType<User>}

const obj:NullAbleUserAndRequireFunction = {name: null, age: 99, money: null, fun: ()=&gt;{}}

kenmori

when test with jest,[material-ui button or tooltips 'addEventListener' of undefined

Error: Uncaught [TypeError: Cannot read property 'addEventListener' of undefined]

console.error node_modules/react-test-renderer/cjs/react-test-renderer.development.js:9215
The above error occurred in the <Connect(OpenDialogIconButton)> component:
in Connect(OpenDialogIconButton) (at ManageApp/index.tsx:373)
in Tooltip (created by WithStyles(Tooltip))
in WithStyles(Tooltip) (at ManageApp/index.tsx:372)

kenmori

WIP

[TypeSript] 共変性と反変性

共変性 と 反変性

Strict function type checking

kenmori

[TypeScript] ]index signature と Recordの空オブジェクトに対する違い

twitter

このような型付をみつけて

const a: Record<string, string> = { 
    doorToDoor: "delivery at door",
    airDelivery: "flying in",

kenmori

Jest encountered an unexpected token

FAIL src/components/AuthorityUserSettingItem/index.test.tsx ● Test suite failed to run

Jest encountered an unexpected token

This usually means that you are trying to import a file which Jest cannot parse, e.g. it's not plain JavaScript.

By default, if Jest sees a Babel config, it will use that to transform your files, ignoring "node_modules".

kenmori

[解決]failed prop type: Invalid prop children supplied to ForwardRef(Typography), expected a ReactNode

titleIconElement

////////
<AppList listTitle="タイトル" appInfos={ownAppInfos} showAllUrl={"/apps"} titleIconElement={<></>} />
<AppList listTitle="タイトル" appInfos={favoriteAppInfos} showAllUrl={"/apps/favorite"} titleIconElement={<></>} />
<AppList listTitle="タイトル" appInfos={presetAppInfos} showAllUrl={"/apps/preset"} titleIconElement={<></>} />

kenmori

【TypeScript】インデックスシグネチャの型定義。string、number

@bukotsunikki

1.初期化時に指定

let obj:{ [key: string]: string} = {}

kenmori

// ここではそれぞれの型引数(T,U)はお互いの関係性は知らない
function someFunction <T, U> (t: T, u: U): T {
  return t;
}

const dog = someFunction(new Dog(), new Cat());

// これを `T extends U` とすることで第二引数のU型を制約とするTになった
function someFunction  (t: T, u: U): T {