001 - JavaScript基本数据类型

var x = 'hello'
	undefined
x
"hello"
x.toLowerCase
	ƒ toLowerCase() { [native code] }
x.toLowerCase()
	"hello"
x.toUpperCase()
	"HELLO"

var xx = Object(x)
	undefined
xx
	String {"hello"}
xx.toLowerCase()
	"hello"
xx.toUpperCase()
	"HELLO"

var x = 'hello';
	undefined
typeof x
	"string"
x.show = function(){return 'showing'}
	ƒ (){return 'showing'}
x.show()
	VM587:1 Uncaught TypeError: x.show is not a function
    	at <anonymous>:1:3
	(anonymous) @ VM587:1
            
var xx = Object(x)
	undefined
typeof xx
	"object"
xx.show = function(){return 'showing'}
	ƒ (){return 'showing'}
xx.show()
	"showing"