{"ScriptPreparationCode":"var obj = { b: false, c: false }","TestCases":[{"Name":"In","Code":"if (!(\u0027a\u0027 in obj)) {\r\n obj.a = new Set();\r\n}\r\n\r\nobj.a.add(42);","IsDeferred":false},{"Name":"!","Code":"if (!obj.a) {\r\n obj.a = new Set();\r\n}\r\n\r\nobj.a.add(42);","IsDeferred":false},{"Name":"!== undefined","Code":"if (obj.a === undefined) {\r\n obj.a = new Set();\r\n}\r\n\r\nobj.a.add(42);","IsDeferred":false},{"Name":"??=","Code":"(obj.a ??= new Set()).add(42);","IsDeferred":false}]}