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In ECMA document we have

The VariableDeclarationListNoIn, VariableDeclarationNoIn and InitialiserNoIn productions are evaluated in the same manner as the VariableDeclarationList, VariableDeclaration and Initialiser productions except that the contained VariableDeclarationListNoIn, VariableDeclarationNoIn, InitialiserNoIn and AssignmentExpressionNoIn are evaluated instead of the contained VariableDeclarationList, VariableDeclaration, Initialiser and AssignmentExpression, respectively.

But what does mean VariableDeclarationNoIn?

MaximPro
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It's a variable declaration whose intialiser must not contain the in operator. Consider

var example = propertyName in object;

which is not a valid VariableDeclarationListNoIn. These kinds of productions are used in the for loop syntax and prevent any ambiguity in things like

for (var example = propertyName in object; example; example = !example) … // invalid
Bergi
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  • Can you look another my question? https://stackoverflow.com/questions/47972903/difference-between-callexpression-and-memberexpression – MaximPro Dec 26 '17 at 16:01