Number.toString returns "incorrect" hexadecimal value

Question

In order to utilize a third party API, I have to convert the ID number to a hexadecimal. I converted the ID with https://www.rapidtables.com/convert/number/decimal-to-hex.html and got 711DD21A11FA9223FEB43849FF1F3569DC024DCE000000000000150000000001. This works when I use it with the API.

My understanding is that you can perform the same conversion with JS with Number().toString(16). However, when I use that function I get 711dd21a11fa9400000000000000000000000000000000000000000000000000.

The latter value does not work with the API. Any insight into why the JS function returns a different value?

Answer 1

Your number is too big for JavaScript.

The Number.MAX_SAFE_INTEGER constant represents the maximum safe integer in JavaScript.

I advise you to use the BigInt data type.

BigInt is a primitive wrapper object used to represent and manipulate primitive bigint values - which are too large to be represented by the number primitive.

Exampe:

// Your number in decimal
const decimalNumber = BigInt("10000000000000000");

// Your number in hex
const hexNumber = decimalNumber.toString(16);

console.log(`Decimal number: ${decimalNumber}`);
console.log(`Hex number: ${hexNumber}`);