{ // start block statement
a: // labeled statement [1]
1 // expression statement
} // end block statement
[ // start array literal
“a” // string value
] // end array literal
vs. ( // start expression statement
{ // start object literal
a: // object literal key
1 // expression statement
} // end object literal statement
[ // begin subscript property access
“a” // string (property key)
] // end subscript property access
) // end expression
[1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...
versus