JavaScript 判断数据类型

1. 通过借助Object.prototype.toString方法来判断

function getObjType (obj) {
  const { toString } = Object.prototype;
  const map = {
    "[object Boolean]": "boolean",
    "[object Number]": "number",
    "[object String]": "string",
    "[object Function]": "function",
    "[object Array]": "array",
    "[object Date]": "date",
    "[object RegExp]": "regExp",
    "[object Undefined]": "undefined",
    "[object Null]": "null",
    "[object Object]": "object"
  }
  if (obj instanceof Element) {
    return "element"
  };
  return map[toString.call(obj)];
}
// 判断函数时，根据函数名判断
// getObjType(getObjType()) 判断的是返回值的类型