I think I got it, var has only global and function scope, this means x and
y are in fact in the same scope, they are collected into the environment
when the function body is evaluated.
(https://262.ecma-international.org/#sec-functiondeclarationinstantiation
step 9)
function test() {
var x
{
var y
}
}
在2023年7月7日星期五 UTC+8 17:32:59<Marja Hölttä> 写道：
> You'll probably want to check out "Static semantics:
> VarScopedDeclarations" (
> https://262.ecma-international.org/#sec-static-semantics-varscopeddeclarations
>
> ) and its usage in
> https://262.ecma-international.org/#sec-globaldeclarationinstantiation .
> Let us know if that didn't help (or if it did) :)
>
>
>
>
> On Fri, Jul 7, 2023 at 9:58 AM Shang Yu <yus...@gmail.com> wrote:
>
>> Hi guys,
>> I'm reading 14.3.2.1
>> <https://262.ecma-international.org/#sec-variable-statement-runtime-semantics-evaluation>
>> section
>> of ecma232 and trying to find out how the following code is evaluated.
>> *var x *// A
>> according to the following part of 14.3.2.1
>>
>> VariableDeclaration : BindingIdentifier
>> 1. Return empty.
>>
>> It seems the code at line A will be a non-op, that is it will do nothing.
>> If this is right, the following code should not run in my understanding,
>> but it did run, how does this happen? Many thanks !
>>
>> ‘use strict’
>> var x
>> x=0
>>
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