Prompt Detail:
Yes, an object can have undefined as a key. In JavaScript, undefined is a primitive value that can be used as a key just like any other value.
For example:
javascriptconst obj = {
undefined: "I am undefined",
};
console.log(obj.undefined); // "I am undefined"
However, it's generally not a good practice to use undefined as a key since it can be easily confused with the undefined value that's returned when a variable has not been assigned a value. It's better to use a more descriptive key name to avoid confusion.
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