about 14.3.2.1 section of ecma262

[Shang Yu]

Hi guys,

I'm reading 14.3.2.1 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

[Marja Hölttä]

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) :)

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[Shang Yu]

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

  }

}