## Does JavaScript have double floating point number precision?

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I know it's an odd question, but does JavaScript have the capacity to work with double's as opposed to single floats? (64 bit floats vs. 32 bits.)

All numbers in JavaScript are 64-bit floating point numbers.

Ref:

http://www.hunlock.com/blogs/The_Complete_Javascript_Number_Reference

http://www.crockford.com/javascript/survey.html

**Does JavaScript have double floating point number precision ,** To figure out what a floating point is, we first start with the idea that there are many The representation of floating points in JavaScript follows the format as Specifically it is a double-precision format, meaning that 64 bits are allocated for According to the ECMA-262 specification (ECMAScript is the specification for Javascript), section 8.5: The Number type has exactly 18437736874454810627 (that is, 2 64 −2 53 +3) values, representing the double-precision 64-bit format IEEE 754 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic Source:

According to the ECMA-262 specification (ECMAScript is the specification for Javascript), section 8.5:

The Number type has exactly 18437736874454810627 (that is, 264−253+3) values, representing the double-precision 64-bit format IEEE 754 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic

Source: http://www.ecma-international.org/publications/files/ecma-st/ECMA-262.pdf (PDF)

**JavaScript Numbers,** These are usually referred to as floating point format and we'll see later numbers and it is the 'double-precision 64-bit binary format IEEE 754 JavaScript Numbers are Always 64-bit Floating Point. Unlike many other programming languages, JavaScript does not define different types of numbers, like integers, short, long, floating-point etc. JavaScript numbers are always stored as double precision floating point numbers, following the international IEEE 754 standard.

In javascript type *number* it's float 64-bit number that support IEEE 754 standard and it's like *double* in C. And you can create 32-bit typed arrays by commands below and control each byte in each component by binding corresponded buffer.

let a = new Float32Array(length); let b = new Float64Array(length);

But note that it's not supported in IE9, here browser compatibility table.

If you want extended presicion like *long double*, you can use double.js or decimal.js library.

**What Every JavaScript Developer Should Know About Floating Points,** In Javascript, all numbers are encoded as double precision floating point That being said, you'll see that floating-point arithmetic is NOT 100% accurate. If you don't need to perform complex arithmetic operations, such as The representation of floating points in JavaScript follows the format as specified in IEEE-754. Specifically it is a double-precision format, meaning that 64 bits are allocated for each floating point. Although it is not the only way to represent floating points in binary, it is by far the most widely used format.

**Here is what you need to know about JavaScript's Number type ,** Double-precision floating-point format is a computer number format, usually occupying 64 bits If an IEEE 754 double-precision number is converted to a decimal string with at least 17 As specified by the ECMAScript standard, all arithmetic in JavaScript shall be done using double-precision floating-point arithmetic. In fact, all numbers in JavaScript are double-precision floating-point numbers, that is, the 64-bit encoding of numbers specified by the IEEE 754 standard—commonly known as “doubles.” If this fact leaves you wondering what happened to the integers, keep in mind that doubles can represent integers perfectly with up to 53 bits of precision.

**Overcoming Javascript numeric precision issues,** In fact, all numbers in JavaScript are double-precision floating-point numbers, can represent integers perfectly with up to 53 bits of precision. You can't represent most decimal fractions exactly with binary floating point types (which is what ECMAScript uses to represent floating point values). So there isn't an elegant solution unless you use arbitrary precision arithmetic types or a decimal based floating point type.

**Double-precision floating-point format,** Until then, let's keep going with a quick primer on the 64-bit floating point number format. What is 64-bit floating point? It is a number format used by computers. It is In modern JavaScript, there are two types of numbers: Regular numbers in JavaScript are stored in 64-bit format IEEE-754, also known as “double precision floating point numbers”. These are numbers that we’re using most of the time, and we’ll talk about them in this chapter.

##### Comments

- But bitwise operations will convert it to a 32 bit integer.
- ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf
- ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf
- This is the only correct answer. It refers to and quotes the ECMAScript specification, which is the only source that matters. The other answer only has sources that are not definitive.