javascript - 使用带点符号的整数键访问 javascript 对象中的属性

Question

为什么我们不能在点表达式中使用整数键来访问属性值？

var obj = {1: 'one', two: '2'}
console.log(obj.1) // error
console.log(obj.two)

Answer 1

如果是dot notation要访问一个值，属性键必须是一个有效的标识符

In this code, property must be a valid JavaScript identifier, i.e. a sequence of alphanumerical characters, also including the underscore ("_") and dollar sign ("$"), that cannot start with a number. For example, object.$1 is valid, while object.1 is not.

您可以使用 bracket notation在这种情况下

obj['1']

规范:Property Accessors