const obj = { hoge: [new Date(2023, 3, 12), 1], fuga: 'foo' }; const objClone = structuredClone(obj); // ディープコピー obj.hoge[1] = 10; console.log(objClone.hoge[1]); // 1 objClone.hoge[0].setFullYear(2050); console.log(obj.hoge[0].getFullYear()); // 2023
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