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| 1 | /**
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| 2 | * Checks if the given value is undefined.
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| 3 | *
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| 4 | * This function tests whether the provided value is strictly equal to `undefined`.
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| 5 | * It returns `true` if the value is `undefined`, and `false` otherwise.
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| 6 | *
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| 7 | * This function can also serve as a type predicate in TypeScript, narrowing the type of the argument to `undefined`.
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| 8 | *
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| 9 | * @param {unknown} x - The value to test if it is undefined.
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| 10 | * @returns {x is undefined} true if the value is undefined, false otherwise.
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| 11 | *
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| 12 | * @example
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| 13 | * const value1 = undefined;
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| 14 | * const value2 = null;
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| 15 | * const value3 = 42;
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| 16 | *
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| 17 | * console.log(isUndefined(value1)); // true
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| 18 | * console.log(isUndefined(value2)); // false
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| 19 | * console.log(isUndefined(value3)); // false
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| 20 | */
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| 21 | declare function isUndefined(x: any): x is undefined;
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| 22 |
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| 23 | export { isUndefined };
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