Confusion between isNaN and Number.isNaN in javascript

Question

I have a confusion in how NaN works. I have executed isNaN(undefined) it returned true . But if I will use Number.isNaN(undefined) it

Answer 1

In shortly,

isNaN()

will check if the convert of value to Number (type) are failed

For example'abc'

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Number.isNaN()

will check if the given value type is Number but not valid number

For example: 'bb'/33