Immediately accessing an object's property

Question

Given these four examples of defining an object and then attempting to immediately access their properties:

{foo: \'bar\'}.foo
// syntax error: unexpected_to         


        

Answer 1

It's not ignored, it's just not recognized as an object here.

{ ... } at the start of a statement is parsed as a Block[spec] of code.

In the case of {foo: 'bar'}.foo, the inner code foo: "bar" is parsed as a LabelledStatement[spec].

So {foo: 'bar'} parses correctly (even if it doesn't do what you expect) but the property access syntax is actually causing the syntax error, as accessing a property on a block is not valid.

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As you noticed the solution is to enclose the object in parentheses:

({foo: 'bar'}).foo

Starting the statement with ( causes the parser to search for an expression inside of the parentheses. {foo: 'bar'} when parsed as an expression is an Object Initializer[spec], as you expected.

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For {foo: 'bar'}['foo'], it's actually parsed as two separate statements: a block ({foo: 'bar'} and an Array initializer (['foo']):

{foo: 'bar'};
['foo'];