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<html><body><h1>JavaScript Numbers</h1><h2>The Number.isNaN() Method</h2><p>Number.isNaN() returns true if the value is Number.NaN (Not a Number), otherwise false.</p><p id="demo"></p><script>let result ="Is true NaN? " + Number.isNaN(true) + "<br>" +"Is true NaN? " + Number.isNaN(false) + "<br>" +"Is undefined NaN? " + Number.isNaN(undefined) + "<br>" +"Is 'NaN' NaN? " + Number.isNaN('NaN') + "<br>" +"Is NaN NaN? " + Number.isNaN(NaN);document.getElementById("demo").innerHTML = result;</script></body></html>