打字稿：表达函数实例属性

Question

赋予JS函数

function someMethod (arg1: boolean) {
  this.state = { };

  // logic and stuff
  return arg1;

如何在打字稿中表达state？

someMethod(true);
someMethod.state; // Property 'state' does not exist on type '(arg1: boolean) => boolean'

Answer 1

如果您希望someMethod是具有属性的普通函数，则可以简单地将其声明为具有呼叫签名和属性，如下所示：

declare const someMethod: {
  (arg1: boolean): boolean;
  state: any; // or whatever type you intend someMethod.state to have
}

但是，如果实际上将someMethod用作构造函数，则强烈建议改写为class：

declare class someClass {
  constructor(arg1: boolean);
  state: any;
}

然后像这样使用它（注意new关键字）：

const instance = new someClass(true);
instance.state = {};