Assignment expressions

Syntax

AssignmentExpression^β :
ConditionalExpression^β
yield [no line break] AssignmentExpression^β
FunctionExpression^β
AssignmentLeftHandSide = AssignmentExpression^β
PostfixExpression CompoundAssignmentPunctuator AssignmentExpression^β
PostfixExpression /= AssignmentExpression^β

AssignmentLeftHandSide :
ArrayPattern
ObjectPattern
PostfixExpression [but not ArrayLiteral or ObjectLiteral]