Object.prototype.toString 返回什么

const isObject = (context) =>
  Object.prototype.toString.call(context) === "[object Object]";

const isObj = isObject({});
console.log(isObj); // true

const isType = (type) => (context) =>
  Object.prototype.toString.call(context) === `[object ${type}]`;

const isArray = isType("Array");
console.log(isArray([])); // true

const [isArray, isString, isObject] = ["Array", "String", "Object"].map(
  (name) => (context) =>
    Object.prototype.toString.call(context) === `[object ${name}]`
);
console.log(isString("abc"));

它的缺点是不能校验自定义类型