// Copyright (C) 2015 André Bargull. All rights reserved. // This code is governed by the BSD license found in the LICENSE file. /*--- info: Compound Assignment Operator evaluates its operands from left to right. description: > The left-hand side expression is evaluated before the right-hand side. Left-hand side expression is MemberExpression: base[prop]. ToPropertyKey(prop) is only called once. Check operator is "x %= y". ---*/ var propKeyEvaluated = false; var base = {}; var prop = { toString: function() { assert(!propKeyEvaluated); propKeyEvaluated = true; return ""; } }; var expr = function() { return 0; }; base[prop] %= expr();