數(shù)據(jù)類型
Undefined
Null
Boolean
String
Symbol
Number
Object
解釋
The Undefined type has exactly one value, called
undefined. Any variable that has not been assigned a value
has the valueundefined.The Null type has exactly one value, called
nullThe Boolean type represents a logical entity having two values, called
trueandfalse.-
The Symbol type is the set of all non-String values that may be used as the key of an Object property (6.1.7). Each possible Symbol value is unique and immutable.
Each Symbol value immutably holds an associated value called [[Description]] that is either undefined or a String value.
