The toString() method returns a string representing the specified BigInt object. The trailing "n" is not part of the string.




Optional. An integer in the range 2 through 36 specifying the base to use for representing numeric values.

Return value

A string representing the specified BigInt object.


If toString() is given a radix less than 2 or greater than 36, a RangeError is thrown.


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

The toString() method parses its first argument, and attempts to return a string representation in the specified radix (base). For radixes above 10, the letters of the alphabet indicate numerals greater than 9. For example, for hexadecimal numbers (base 16) a through f are used.

If the radix is not specified, the preferred radix is assumed to be 10.

If the bigIntObj 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 bigIntObj preceded by a - sign, not the two's complement of the bigIntObj.


Using toString

17n.toString();      // '17'
66n.toString(2);     // '1000010'
254n.toString(16);   // 'fe'
-10n.toString(2);    // -1010'
-0xffn.toString(2);  // '-11111111'

Negative-zero BigInt

There is no negative-zero BigInt as there are no negative zeros in integers. -0.0 is an IEEE floating-point concept that only appears in the JavaScript Number type.

(-0n).toString();      // '0' 
BigInt(-0).toString(); // '0'


ECMAScript (ECMA-262)
The definition of 'BigInt.prototype.toString()' in that specification.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
toStringChrome Full support 67Edge Full support 79Firefox Full support 68IE No support NoOpera Full support 54Safari Full support 14WebView Android Full support 67Chrome Android Full support 67Firefox Android Full support 68Opera Android Full support 48Safari iOS Full support 14Samsung Internet Android Full support 9.0nodejs Full support 10.4.0


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See also