//2.toString()
//转字符串。
//进制转换。num.toString(2/8/10/16)
//最好的数据类型的检查方法。
console.log(Object.prototype.toString.call('abc').slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(5).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(true).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(null).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(undefined).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call([]).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call({}).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(/\d/).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(function(){}).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(new Date).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(new Set).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(new Map).slice(8,-1).toLowerCase());
console.log(Object.prototype.toString.call(Symbol('hello')).slice(8,-1).toLowerCase());