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Version: 3.13.0

Number.prototype.toString()

The toString() method returns a string representing the specified number value.

Syntax​

toString()
toString(radix)

Parameters​

  • radix optional
    • : An integer in the range 2 through 36 specifying the base to use for representing the number value. Defaults to 10.

Return value​

A string representing the specified number value.

Exceptions​

  • RangeError
    • : Thrown if radix is less than 2 or greater than 36.

Description​

The Number object overrides the toString method of Object; it does not inherit Object.prototype.toString(). For Number values, the toString method returns a string representation of the value in the specified radix.

For radixes above 10, the letters of the alphabet indicate digits greater than 9. For example, for hexadecimal numbers (base 16) a through f are used.

If the specified number value is negative, the sign is preserved. This is the case even if the radix is 2; the string returned is the positive binary representation of the number value preceded by a - sign, not the two's complement of the number value.

Both 0 and -0 have "0" as their string representation. Infinity returns "Infinity" and NaN returns "NaN".

If the number is not a whole number, the decimal point . is used to separate the decimal places. Scientific notation is used if the radix is 10 and the number's magnitude (ignoring sign) is greater than or equal to 1021 or less than 10-6. In this case, the returned string always explicitly specifies the sign of the exponent.

console.log((10 ** 21.5).toString()); // "3.1622776601683794e+21"
console.log((10 ** 21.5).toString(8)); // "526665530627250154000000"

The toString() method requires its this value to be a Number primitive or wrapper object. It throws a TypeError for other this values without attempting to coerce them to number values.

Because Number doesn't have a [Symbol.toPrimitive]() method, JavaScript calls the toString() method automatically when a Number object is used in a context expecting a string, such as in a template literal. However, Number primitive values do not consult the toString() method to be coerced to strings — rather, they are directly converted using the same algorithm as the initial toString() implementation.

Number.prototype.toString = () => "Overridden";
console.log(`${1}`); // "1"
console.log(`${new Number(1)}`); // "Overridden"