JavaScript中一长串整数的转换问题

Question

I'm trying to convert a long string which has only integers to numbers.

var strOne = '123456789123456789122';
parseInt(strOne, 10);
// => 123456789123456800000

var strTwo = '1234567891234567891232';
parseInt(strTwo, 10);
// => 1.234567891234568e+21

The expected output should be the same as strOne and strTwo but that isn't happening here. While converting the string to a number, the output gets changed.

What's the best way to fix this issue?

Answer 1

You number is unfortunately too large and gets wrapped when the conversion is done.

The largest integer you can express in JavaScript is 2^53-1 , it is given by Number.MAX_SAFE_INTEGER , see the MDN doc here .

The reasoning behind that number is that JavaScript uses double-precision floating-point format numbers as specified in IEEE 754 and can only safely represent numbers between -(2^53 - 1) and 2^53 - 1.

 console.log(Number.MAX_SAFE_INTEGER); 

If you want to work with numbers bigger than this limit, you'll have to use a different representation than Number such as String and use a library to handle operations (see the BigInteger library for example).

Answer 2

BigInt is now available in browsers.

BigInt is a built-in object that provides a way to represent whole numbers larger than 253, which is the largest number JavaScript can reliably represent with the Number primitive.

value The numeric value of the object being created. May be a string or an integer.

 var strOne = '123456789123456789122'; var intOne = BigInt(strOne); var strTwo = '1234567891234567891232'; var intTwo = BigInt(strTwo); console.log(intOne, intTwo);