【Symbol】
The Symbol()
function returns a value of type symbol. it does not support the syntax "new Symbol()
".
Every symbol value returned from Symbol()
is unique. A symbol value may be used as an identifier for object properties; this is the data type's only purpose.
The data type symbol is a primitive data type.
var sym1 = Symbol(); var sym2 = Symbol('foo'); var sym3 = Symbol('foo');
The above code creates three new symbols.
The following syntax with the new
operator will throw a TypeError
:
var sym = new Symbol(); // TypeError
链接:https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol