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What is JavaScript's Max Int? What's the highest Integer value a Number can go to without losing precision?
What is the maximum integer in javascript? I have a variable that starts in 0 and adds 100 each 0.1 seconds. What is the maximum number it can reach?
BTW, I thought this question had been answered before but I couldn't find it. If it is answered, please send me a link to it =) thanks!
JavaScript numbers are IEE 794 floating point double-precision values. There's a 53-bit mantissa (from memory), so that's pretty much the limit.
Now there are times when JavaScript semantics call for numbers to be cast to a 32-bit integer value, like array indexing and bitwise operators.
A javascript variable can have any value you like. If native support isn't sufficient, there are various libraries that provide support for unlimited precision arithmetic (e.g. BigInt.js).
The largest value for the ECMAScript Number Type is +ve infinity (but infinity isn't a number, it's a concept). The largest numeric value is given by Number.MAX_VALUE, which is just the maximum value representable by an IEEE 754 64-bit double-precision number.
Some quirks:
var x = Number.MAX_VALUE;
var y = x - 1;
var z = x - 2;
x == y; // true
x == z; // false
The range of contiguous integers representable in ECMAScript is from -2^53 to +2^53. The largest exponent is 2^1023.
It is 1.7976931348623157e+308
to try it yourself code it
CODE
alert(Number.MAX_VALUE);
http://jsfiddle.net/XHcZx/
Related
This question already has answers here:
What is JavaScript's highest integer value that a number can go to without losing precision?
(21 answers)
Closed 4 days ago.
I was expecting 6145390195186705543 but gave me 6145390195186705000.
This is my code:
var str = '6145390195186705543';
var num = parseInt(str);
console.log(num)
JavaScript uses 64-bit floating point numbers, which can represent numbers in the range -(2^53 - 1) to (2^53 - 1). In this case, the number 6145390195186705543 is out of this range and cannot be accurately represented in JavaScript. When trying to convert the string "6145390195186705543" to a number using the parseInt() function, JavaScript cannot represent the number exactly and rounds it to the nearest floating point number, resulting in 6145390195186705000.
To work with such large numbers, you can use special libraries for working with large arithmetic, such as BigInt or BigNumber.
This question already has answers here:
What is JavaScript's highest integer value that a number can go to without losing precision?
(21 answers)
Closed 4 years ago.
I have tried JavaScript Number method and it returns unexpected results.
If i pass 192000000000000005 value into Number() method. It returns 192000000000000000, without 5.
If I Pass 19200000000000005 value, it returns 19200000000000004, which is unexpected.
What is that meaning of those results? You can find the below screenshot too.
Chrome Console:
192000000000000005 can not be represented by a Number in javascript, due to the limitations of 64bit floating point representation
The Maximum integer that is safe (i.e. all integers up to that integer can be represented without gaps) is Number.MAX_SAFE_INTEGER === 9,007,199,254,740,991
you can see that's 16 digits - so 18 digits is not safe, and 19 (whatever, you've never tried) won't work either -
Note, the actual definition of MAX_SAFE_INTEGER is
the largest integer n, where n and n + 1 are both exactly representable as a Number value
console.log(9007199254740991) //=> 9007199254740991
console.log(9007199254740992) //=> 9007199254740992
console.log(9007199254740993) //=> 9007199254740992
So, while 9007199254740992 is representable as a Number, because 9007199254740993 also has the same value when stored in a 64bit float, it is not "safe"
note 9007199254740991 is 2**53 - 1 - which makes sense when you know that 64bit floating point has a 53 bit mantissa
Mozilla Developer Network Documentation
This question already has answers here:
What is JavaScript's highest integer value that a number can go to without losing precision?
(21 answers)
Closed 7 years ago.
I have data like this:
var currentValue="12345678901234561";
and I'm trying to parse it:
var number = parseInt(currentValue, 10) || 0;
and my result is:
number = 12345678901234560
now lets try:
currentValue="12345678901234567"
in this case parseInt(currentValue,10) will result in 12345678901234568
Can anyone explain me why parseInt is adding/substracting 1 from values provided by me?
Can anyone explain me why parseInt is adding/substracting 1 from values provided by me?
It's not, quite, but JavaScript numbers are IEEE-754 double-precision binary floating point (even when you're using parseInt), which have only about 15 digits of precision. Your number is 17 digits long, so precision suffers, and the lowest-order digits get spongy.
The maximum reliable integer value is 9,007,199,254,740,991, which is available from the property Number.MAX_SAFE_INTEGER on modern JavaScript engines. (Similarly, there's Number.MIN_SAFE_INTEGER, which is -9,007,199,254,740,991.)
Some integer-specific operations, like the bitwise operators ~, &, and |, convert their floating-point number operands to signed 32-bit integers, which gives us a much smaller range: -231 (-2,147,483,648) through 231-1 (2,147,483,647). Others, like <<, >>, and >>>, convert it to an unsigned 32-bit integer, giving us the range 0 through 4,294,967,295. Finally, just to round out our integer discussion, the length of an array is always a number within the unsigned 32-bit integer range.
We know that Java does not handle underflows and overflows, but how does Javascript handle these for integers?
Does it go back to a minimum/maximum? If yes, which minimum/maximum?
I need to split a string and compute a hash value based on its characters.
In a simple test, when I try this:
var max = Number.MAX_VALUE;
var x = max + 10;
var min = Number.MIN_VALUE;
var y = min / 10;
I find that x and max have the same value (in Chrome, IE and Firefox) so it appears that some overflows are just pegged to the max value. And, y gets pegged to 0 so some underflows seem to go to zero.
Ahhh, but it is not quite that simple. Not all overflows go to Number.MAX_VALUE and not all underflows go to Number.MIN_VALUE. If you do this:
var max = Number.MAX_VALUE;
var z = max * 2;
Then, z will be Infinity.
It turns out that it depends upon how far you overflow/underflow. If you go too far, you will get INFINITY instead. This is because of the use of IEEE 754 round-to-nearest mode where the max value can be considered nearer than infinity. See Adding to Number.MAX_VALUE for more detail. Per that answer, values of 1.7976931348623158 × 10308 or greater round to infinity. Values between Number.MAX_VALUE and that will round to Number.MAX_VALUE.
To, make things even more complicated, there is also something as gradual underflow which Javascript supports. This is where the mantissa of the floating point value has leading zeroes in it. Gradual underflow allows floating point to represent some smaller numbers that it could not represent without that, but they are represented at a reduced precision.
You can see exactly where the limits are:
>>> Number.MAX_VALUE + 9.979201e291
1.7976931348623157e+308
>>> Number.MAX_VALUE + 9.979202e291
Infinity
Here's a runnable snippet you can try in any browser:
var max = Number.MAX_VALUE;
var x = max + 10;
var min = Number.MIN_VALUE;
var y = min / 10;
var z = max * 2;
document.getElementById("max").innerHTML = max;
document.getElementById("max10").innerHTML = x;
document.getElementById("min").innerHTML = min;
document.getElementById("min10").innerHTML = y;
document.getElementById("times2").innerHTML = z;
body {
font-family: "Courier New";
white-space:nowrap;
}
Number.MAX_VALUE = <span id="max"></span><br>
Number.MAX_VALUE + 10 = <span id="max10"></span><br>
<br>
Number.MIN_VALUE = <span id="min"></span><br>
Number.MIN_VALUE / 10 = <span id="min10"></span><br>
<br>
Number.MAX_VALUE * 2 = <span id="times2"></span><br>
The maximum and minimum is +/- 9007199254740992
Try these Number type properties:
alert([Number.MAX_VALUE, Number.MIN_VALUE]);
From the ECMAScript 2020 language specification, section "The Number Type":
Note that all the positive and negative mathematical integers whose magnitude is no
greater than 253 are representable in the Number type (indeed, the
mathematical integer 0 has two representations, +0 and −0).
Test:
var x = 9007199254740992;
var y = -x;
x == x + 1; // true !
y == y - 1; // also true !
Number
In JavaScript, number type is 64 bit IEEE 754 floating point number which is not an integer. So it don't follow common patterns of integer overflow / underflow behavior in other languages.
As the floating point number use 53 bits for base part. It may represent numbers in range Number.MIN_SAFE_INTEGER to Number.MAX_SAFE_INTEGER (-253+1 to 253-1) without floating point errors. For numbers out of this range, it may be rounded to nearest number available, or may be Infinity if it is too large.
Bit-wise operator
Bit-wise operator treat operand 32 bit integers. And common integer overflow may happened as in other languages. Only last 32 bits may be kept after calculate. For example, 3<<31 would results -2147483648.
>>> treat operand as unsigned 32 bit integers. All other operator treat operand as signed 32 bit integers. If you want to convert signed integer to unsigned, you may write value >>> 0 to do the trick. To convert back, use value | 0.
If you want to shift an integer with 33, it will actually be shifted with 1.
BigInt
Just like Java's java.math.BigInteger, BigInt supports unbounded integers (still bound by your memory limit though). So integer overflow may never happen here.
TypedArray
For most TypedArray types, when an integer out of supported range assigned, it got truncated as what other languages do when converting integers, by keeping least significant bits. For example new Int8Array([1000])[0] got -24.
Uint8ClampedArray is a bit different from other TypedArray's. Uint8ClampedArray supports integers in range 0 ~ 255. When numbers out of range is used, 0 or 255 will be set instead.
asm.js
The same rules for bit-wise operator applied here. The value would be trucked back as what | 0 or >>> 0 do.
This question already has answers here:
Why is 9999999999999999 converted to 10000000000000000 in JavaScript?
(6 answers)
Closed 8 years ago.
Converting string to number produces incremented value:
var n = '9999999999999999';
console.log(n); // -> 9999999999999999
var nn = Number(n)
console.log(nn); // -> 10000000000000000
How to avoid this?
9999999999999999 is treated internally in JavaScript as a floating-point number. It cannot be accurately represented in IEEE 754 double precision as it would require 54 bits of precision (the number of bits is log2(9999999999999999) = 53.150849512 and since fractional bits do not exist, the result must be rouned up) while IEEE 754 provides only 53 bits (1 implict bit + 52 explicitly stored bits of the mantissa) - one bit less. Hence the number simply gets rounded.
Since only one bit is lost in this case, even 54-bit numbers are exactly representable, since they nevertheless contain 0 in the bit, which gets lost. Odd 54-bit numbers are rounded to the nearest value that happens to be a doubled even 53-bit number given the default unbiased rounding mode of IEEE 754.
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