Number.isNaN()

O método Number.isNaN() determina se o valor passado é NaN. Esta é uma versão mais robusta que isNaN().

Sintaxe

Number.isNaN(valor)

Parâmetros

valor

O valor a ser testado se é NaN.

Descrição

Due to both equality operators, == and ===, evaluating to false when checking if NaN is NaN, the function Number.isNaN() has become necessary. This situation is unlike all other possible value comparisons in JavaScript.

In comparison to the global isNaN() function, Number.isNaN() doesn't suffer the problem of forcefully converting the parameter to a number. This means it is now safe to pass values that would normally convert to NaN, but aren't actually the same value as NaN. This also means that only values of the type number, that are also NaN, return true.

Exemplos

Number.isNaN(NaN);        // true
Number.isNaN(Number.NaN); // true
Number.isNaN(0 / 0)       // true

// e.g. these would have been true with global isNaN()
Number.isNaN("NaN");      // false
Number.isNaN(undefined);  // false
Number.isNaN({});         // false
Number.isNaN("blabla");   // false

// These all return false
Number.isNaN(true);
Number.isNaN(null);
Number.isNaN(37);
Number.isNaN("37");
Number.isNaN("37.37");
Number.isNaN("");
Number.isNaN(" ");

Polyfill

Number.isNaN = Number.isNaN || function(value) {
    return typeof value === "number" && isNaN(value);
}

Especificações

Compatibilidade dos browsers

Ver também

• Number
• isNaN()