常见的类型转换

JavaScript中常见的隐式转换数据类型的规则总结:

类型	值	to Boolean	to Number	to String
Boolean	true	true	1	"true"
Boolean	false	false	0	"false"
Number	123	true	123	"123"
Number	Infinity	true	Infinity	"Infinity"
Number	0	false	0	"0"
Number	NaN	false	NaN	"NaN"
String	""	false	0	""
String	"123"	true	123	"123"
String	"123abc"	true	NaN	"123abc"
String	"abc"	true	NaN	"abc"
Null	null	false	0	"null"
Undefined	undefined	false	NaN	"undefined"
Function	function() {}	true	NaN	"function(){}"
Object	{}	true	NaN	"[object Object]"
Array	[]	true	0	""
Array	["abc"]	true	NaN	"abc"
Array	["123"]	true	123	"123"
Array	["123", "abc"]	true	NaN	"123, abc"