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Note that in case no type check matches, the error has to be re-thrown! This code can be omitted if the original code contains a catch clause with an untyped or * typed error variable.

Operators

TODO

&&=

TODO

||=

Besides as and is, which are discussed in the Interfaces section, only two operators are known to be missing in JavaScript, namely short-circuit-and-assignment (&&=) and short-circuit-or-assignment (||=).

For both operators, the trick is that both the left-hand-side and right-hand-side expression are not evaluated too often. To achieve this, we introduce auxiliary variables like for for each. The code transformation examples are for &&= only, as ||= works analogously.

Simple Pattern:

ActionScript:

<identifier> &&= <rhs>

JavaScript:

<identifier> = <identifier> && <rhs>

Complex Pattern:

If the left-hand-side can be split into two expressions, where the first evaluates to some object and the second to some property, do so and rewrite:

ActionScript:

<exp1>[<exp2>] &&= <rhs>

JavaScript:

var $0 = <exp1>, $1 = <exp2>;
$0[$1] = $0[$1] && <rhs>;

Note that foo().y is the same as foo()'y' and thus also matches this pattern.TODO