通过拆分获取类型推断

题目

防抖函数的类型标注, 要求防抖函数的返回类型为void

ts

namespace Question {
  declare function debounce(obj: Function): Function;

  function handler(a: number, b: number) {
    return a + b;
  }

  const dHandler = debounce(handler);

  dHandler();
}

namespace Question {
  declare function debounce(obj: Function): Function;

  function handler(a: number, b: number) {
    return a + b;
  }

  const dHandler = debounce(handler);

  dHandler();
}

解法

ts

namespace Answer {
  declare function debounce<A extends any[], R>(
    fn: (...args: A) => R,
    duration?: number
  ): (...args: A) => void;

  function handler(a: number, b: number) {
    return a + b;
  }

  const dHandler = debounce(handler);

  dHandler(3, 4);
}

namespace Answer {
  declare function debounce<A extends any[], R>(
    fn: (...args: A) => R,
    duration?: number
  ): (...args: A) => void;

  function handler(a: number, b: number) {
    return a + b;
  }

  const dHandler = debounce(handler);

  dHandler(3, 4);
}