• 코드:
​x
 
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<!DOCTYPE html>
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<html lang="ko">
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​
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<head>
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    <meta charset="UTF-8">
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    <title>JavaScript Number Object</title>
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</head>
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​
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<body>
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​
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    <h1>null, undefined, NaN, Infinity</h1>
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​
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    <script>
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        document.write((typeof null) + "<br>");
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        document.write((typeof undefined) + "<br>");
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        document.write((typeof NaN) + "<br>");
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        document.write((typeof Infinity) + "<br><br>");
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​
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        document.write(Boolean(null) + "<br>");
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        document.write(Boolean(undefined) + "<br>");
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        document.write(Boolean(NaN) + "<br>");
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        document.write(Boolean(Infinity) + "<br><br>");
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​
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        document.write(Number(null) + "<br>");
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        document.write(Number(undefined) + "<br>");
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        document.write(Number(NaN) + "<br>");
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        document.write(Number(Infinity) + "<br><br>");
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​
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        document.write(String(null) + "<br>");
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        document.write(String(undefined) + "<br>");
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        document.write(String(NaN) + "<br>");
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        document.write(String(Infinity));
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    </script>
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</body>
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​
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</html>