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function doTest(expected, v) {
assertEq(Object.prototype.toString.call(v), expected)
}
function Dummy() {}
// Basic primitive cases
doTest("[object Undefined]", undefined);
doTest("[object Null]", null);
doTest("[object String]", "");
doTest("[object Number]", 12);
doTest("[object Number]", 12.34);
doTest("[object Boolean]", true);
doTest("[object Symbol]", Symbol());
doTest("[object BigInt]", 1234n);
// Exotic objects with builtinTag
doTest("[object Array]", []);
(function() {
doTest("[object Arguments]", arguments);
})();
doTest("[object Function]", () => {});
doTest("[object Error]", new Error);
doTest("[object Date]", new Date);
doTest("[object RegExp]", /i/);
// Exotic objects with @@toStringTag
doTest("[object Map]", new Map);
doTest("[object Set]", new Set);
doTest("[object JSON]", JSON);
doTest("[object Math]", Math);
// Normal object cases
doTest("[object Object]", {});
doTest("[object Object]", new Dummy);
doTest("[object Foo]", { [Symbol.toStringTag]: "Foo" });
// Test the receiver of Symbol.toStringTag
let receiver1;
let object1 = {
__proto__: {
get [Symbol.toStringTag]() {
receiver1 = this;
}
}
};
doTest("[object Object]", object1);
assertEq(receiver1, object1);
//// BELOW THIS LINE TAMPERS WITH GLOBAL
// Set a toStringTag on the global String.prototype
let receiver2;
Object.defineProperty(String.prototype, Symbol.toStringTag, { get: function() {
receiver2 = this;
return "XString";
}});
doTest("[object XString]", "");
assertEq(Object.getPrototypeOf(receiver2), String.prototype);
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