I have a string value ' 9223372036854775807 '. I use Number() function in JavaScript to convert it to a number value using the following Code
var numericVal = Number(' 9223372036854775807 ');
when i check the value in numericVal, it is 9223372036854776000. How can I get the equivalent value for the string representing the Number?
Ordinary JavaScript numbers are Double Precision Floats; the largest integer that can be precisely stored is 253 (9007199254740992).
If you need to deal precisely with such large numbers, you can either:
BigInt data type. Create one with BigInt("9223372036854775807") or 9223372036854775807n. Note that BigInt did not exist when this question was asked, but is now classed as "widely available" by MDN, which says it has "been available across browsers since September 2020". Or...
Double Precision Float can only be precise between -2^53 and 2^53. JavaScript will attempt to store the number, but it will not be able to be precise due to the object type. Also note that JavaScript arithmetic operators work in 64-bit, but bitwise and shift operators work in 32-bits. If you are working with numbers of this size, you will need to use a non-native object such as big.jsYou can compare strings that represent big integers as strings-
a longer string of integers is larger, otherwise compare characters in order.
You can sort an array of integer-strings
function compareBigInts(a, b){
if(a.length== b.length) return a>b? 1:-1;
return a.length-b.length;
}
or return the larger of two strings of digits
function getBiggestBigInts(a, b){
if(a.length== b.length) return a>b? a:b;
return a.length>b.length? a: b;
}
//examples
var n1= '9223372036854775807', n2= '9223372056854775807',
n3= '9223',n2= '9223372056854775817',n4= '9223372056854775';
getBiggestBigInts(n1,n2);>> 9223372056854775807
[n1,n2,n3,n4].sort(compareBigInts);>>
9223
9223372056854775
9223372036854775807
9223372056854775817
Just make sure you are comparing strings.
(If you use '-' minus values,a 'bigger' string value is less)
By the way,you sort big decimals by splitting on the decimal point and comparing the integer parts. If the integers are the same length and are equal, look at the the decimal parts.
It's seems that your number is greater than 2^53, biggest integer number in javascript which can be represented without loosing precision (see this question).
If you really need to operate big numbers, you could use special libraries like this one: https://github.com/peterolson/BigInteger.js
The problem why Number('9223372036854775807') produce 9223372036854776000 is that JavaScript have limited precision (up to 16 digits) and you need 19 digits.
One of solutions might be using of java script big-numbers library:
// Initializa library:
var bn = new BigNumbers();
// Create numbers to compare:
var baseNumber = bn.of('9223372036854775807');
var toCompareNumber = bn.of('9223372036854775808');
// Compare:
if(baseNumber.lessOrEquals(toCompareNumber)) {
console.log('This should be logged');
} else {
console.log('This should NOT be logged');
}
if(valueToCompare.startsWith('-')) { valueToCompare = valueToCompare.substring(1); isValid = !(valueToCompare>9223372036854775808); } else { isValid = !(valueToCompare>9223372036854775807); }