js的类型检测方式

1.typeof

console.log(typeof "");
console.log(typeof 1);
console.log(typeof true);
console.log(typeof null);
console.log(typeof undefined);
console.log(typeof []);
console.log(typeof function(){});
console.log(typeof {});

2.instanceof

1 console.log("1" instanceof String);
2 console.log(1 instanceof Number);
3 console.log(true instanceof Boolean);
4 //            console.log(null instanceof Null);
5 //            console.log(undefined instanceof Undefined);
6 console.log([] instanceof Array);
7 console.log(function(){} instanceof Function);
8 console.log({} instanceof Object);

3.constructor

4.Object.prototype.toString.call()