ECMA-334: 12.3.3.5 If statements

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12.3.3.5 If statements

For an if statement stmt of the form:

if ( expr ) then-stmt else else-stmt

• v has the same definite assignment state at the beginning of expr as at the beginning of stmt.

• If v is definitely assigned at the end of expr, then it is definitely assigned on the control flow transfer to then-stmt and to either else-stmt or to the end-point of stmt if there is no else clause.

• If v has the state "definitely assigned after true expression" at the end of expr, then it is definitely assigned on the control flow transfer to then-stmt, and not definitely assigned on the control flow transfer to either else-stmt or to the end-point of stmt if there is no else clause.

• If v has the state "definitely assigned after false expression" at the end of expr, then it is definitely assigned on the control flow transfer to else-stmt, and not definitely assigned on the control flow transfer to then-stmt. It is definitely assigned at the end-point of stmt if and only if it is definitely assigned at the end-point of then-stmt.

• Otherwise, v is considered not definitely assigned on the control flow transfer to either the then-stmt or else-stmt, or to the end-point of stmt if there is no else clause.