TS TypeScript常用语法

vue组件props转为TS类型

import { ExtractPropTypes } from 'vue';
const props = {
  layout: {
    type: String as PropType<'inline' | 'grid' | 'vertical'>,
    default: 'inline',
  },
  labelWidth: {
    type: [Number, String] as PropType<number | 'auto'>,
    default: 'auto',
  },
  colon: {
    type: Boolean,
  },
  onChange: Function as PropType<(val: string) => void>,
};
// 语句
type Props = ExtractPropTypes<typeof props>;
// 最终类型的值
// type Props = {
//   layout: 'inline' | 'grid' | 'vertical';
//   labelWidth: number | 'auto';
//   colon: boolean;
//   onChange?: ((val: string) => void) | undefined
// };

取一个函数返回值的类型

function getVal() {
  return {
    name: 'jack',
    list: [
      {
        type: 'string',
        key: 'a',
      },
    ],
    status: true,
  };
}
// 语句
type Val = ReturnType<typeof getVal>
// 最终类型的值
// type Val = {
//   name: string;
//   list: { type: string; key: string }[];
//   status: boolean;
// };

将TS类型的所有值转为可选值

type Val = {
  name: string;
  list: { type: string; key: string }[];
  status: boolean;
};
// 语句
type NewVal = Partial<Val>
// 最终类型的值
// type NewVal = {
//   name?: string | undefined;
//   list?: { type: string; key: string }[] | undefined;
//   status?: boolean | undefined;
// };

将TS类型的所有值转为必选值

type Val = {
  name?: string | undefined;
  list?: { type: string; key: string }[] | undefined;
  status?: boolean | undefined;
};
// 语句
type NewVal = Required<Val>
// 最终类型的值
// {
//    name: string;
//    list: { type: string; key: string }[];
//    status: boolean;
// };

获取Promise返回值的类型

const fn= new Promise<string>((resolve) => {
  resolve('')
})
type PickPromise<P> = P extends Promise<infer R> ? R : P

type PromiseType = PickPromise<typeof fn>
// 最终类型的值
// type PromiseType = string