This question already has answers here:
Why are two different numbers equal in JavaScript?
(4 answers)
How to deal with floating point number precision in JavaScript?
(47 answers)
Is floating point math broken?
(31 answers)
Closed 3 years ago.
Why 888888888888888888888 equals 888888888888888900000 in JavaScript
console.log(888888888888888888888 === 888888888888888900000)
in chrome console
That is because integers can only be precisely represented in JavaScript up to 2^53 - 1
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/MAX_SAFE_INTEGER
The problem is that, after 2^53 - 1, there is not enough bits to represent the number. So, when you set a higher number, you lose information and what you are actually storing in memory is not reliable. In your case, these 2 numbers, after converting to binary, are the same. That is why they are equal
Related
This question already has answers here:
Node.js Maximum Safe Floating-point Number
(4 answers)
What is JavaScript's highest integer value that a number can go to without losing precision?
(21 answers)
Is floating point math broken?
(31 answers)
Closed 2 years ago.
I am developing a react app and i need to format some numbers using toLocaleString function and i realize that the decimal part of the number changes to zero when the number is very
(10000.25).toLocaleString('en',{maximumFractionDigits: 2, minimumFractionDigits: 2});
//Output: 10,000.25
(10000000000000000000.25).toLocaleString('en',{maximumFractionDigits: 2, minimumFractionDigits: 2});
//Output: 10,000,000,000,000,000,000.00
why is this so? is it a bug or am I missing something?
Javascript compiler cannot handle very large numbers. Use Number.MAX_SAFE_INTEGER to check the last number it can handle. Try to consider using string type from the beginning if these numbers are not calculated (Maybe if you get it from an API kind of), or try using BigInt type.
For floating point, the maximum number it can handle to a precision of 1 decimal digit is 562949953421311 and it differs for other digits. This has been referred here. Try using the BigNumber class in your case.
This question already has answers here:
How to deal with floating point number precision in JavaScript?
(47 answers)
Closed 5 years ago.
for example in javascript addition of 1 + 0.59 is 1.5899999999999999 but I want output of 1.59 which looks right to me.
Use .toFixed() to round your number.
alert((1+0.58999999999).toFixed(2));
This question already has answers here:
javascript large integer round because precision? (why?)
(2 answers)
What is JavaScript's highest integer value that a number can go to without losing precision?
(21 answers)
Closed 7 years ago.
number 10205558742352809 gets reduced to 10205558742352808.
What?
TL;DR: Floating-point numbers can be screwy.
Long Answer
Javascript uses 64-bit floating point numbers (IEEE-754). The binary that makes up a floating point number is composed of 3 parts: sign bit (1 bit), exponent field (11 bits), and the significand field (52 bits). There are plenty of sources online that go into further detail about how this works.
If we convert 10205558742352809 to it's binary format then interpret that as hexadecimal for readability we get:
434220F367C941D4
Which is the same thing you'd get for 102...09. Compare that with 102...10:
434220F367C941D5
So 102...09 is not directly representable in IEEE-754 and in fact lies on the border between 102...08 and 102...10.
This question already has answers here:
Large integers in javascript (more the 2^53-1)
(2 answers)
What is JavaScript's highest integer value that a number can go to without losing precision?
(21 answers)
Closed 7 years ago.
I am making a calculator in JavaScript that needs to be able to do precise math on numbers larger than 2^53, which is 9007199254740992. Is there any way to do this?
You can use the "strint" library https://github.com/rauschma/strint.
For example:
> var strint = require("./strint");
> strint.add("9007199254740992", "1")
'9007199254740993'
This question already has answers here:
Is floating point math broken?
(31 answers)
Closed 8 years ago.
This code snippet:
Math.pow(10,20)+20000 == Math.pow(10,20) + 10000
evaluates to true. Is this a JS bug?
No. Javascript uses floating point numbers to represent large values, and the value 1020 exceeds the precision of the floating point numbers. When you add a relatively tiny value such as 20000 or 10000 to the result, the resulting sums are indistinguishable.