How do you check if a value is NaN in JavaScript?

Sometimes, it is requirement to check whether a variable is number or coerced to a number or not.

We can utilize isNaN method available in Number object to check it.

The isNaN method returns true only when value is NaN or coerces to NaN.

Here is an example:

const var1 = 34;
if (Number.isNaN(var1)) {
  console.log("NaN value");
} else {
  console.log("Not a NaN value");
}

This will print the following

Not a NaN value

Here is second example:

const var2 = "hello world";
if (Number.isNaN(var2)) {
  console.log("NaN value");
} else {
  console.log("Not a NaN value");
}

This will print the following:

NaN value

here Number.isNaN(var2) coerces to NaN value.

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