JavaScript Numbers (original) (raw)

Last Updated : 11 Jul, 2025

JavaScript numbers are primitive data types, and unlike other programming languages, you don't need to declare different numeric types like int, float, etc. JavaScript numbers are always stored in double-precision 64-bit binary format IEEE 754. This format stores numbers in 64 bits:

Numeric Types in JavaScript

In JavaScript, numbers play an important role, and understanding their behavior is essential for effective programming. Let’s explore the various aspects of numeric types in JavaScript.

1. The Only Numeric Type

As we know, JavaScript has only one numeric type: the **double-precision 64-bit binary format IEEE 754, whichmeans that it doesn’t differentiate between integers and floating-point numbers explicitly. Instead, it uses a unified approach for all numeric values.

2. Scientific Notation

JavaScript allows writing extra-large or extra-small numbers using scientific (exponent) notation.

JavaScript `

let a = 156e5; let b = 156e-5; console.log(a); console.log(b);

`

3. Integer Precision

Integers (numbers without a period or exponent notation) are accurate up to 15 digits.

JavaScript `

let a = 999999999999999; let b = 9999999999999999; console.log(a); console.log(b);

`

Output

999999999999999 10000000000000000

4. Floating Point Precision

Floating point arithmetic is **not always 100% accurate due to binary representation limitations.

**Example

let x = 0.22 + 0.12; //x will be 0.33999999999999997

**To solve this problem, multiply and divide:

let x = (0.22 * 10 + 0.12 * 10) / 10; // x will be **0.34

JavaScript `

let x = 0.22 + 0.12; let y = (0.22 * 10 + 0.12 * 10) / 10; console.log(x); console.log(y);

`

Output

0.33999999999999997 0.34

5. Adding Numbers and Strings

// Adding two numbers let x = 10; let y = 15; let z = x + y; console.log(z);

// Concatenating two strings:

let a = "10"; let b = "30"; let c = a + b; console.log(c);

`

6. Numeric Strings

JavaScript automatically converts the numeric strings to numbers in most operations like.

JavaScript `

let x = "100" / "10"; let y = "100" * "10"; let z = "100" - "10"; console.log(x); console.log(y); console.log(z);

`

**Number Literals

**The types of number literals You can use decimal, binary, octal, and hexadecimal.

**1. Decimal Numbers

JavaScript Numbers does not have different types of numbers(ex: int, float, long, short) which other programming languages do. It has only one type of number and it can hold both with or without decimal values.

JavaScript `

let a=33; let b=3.3; console.log(a); console.log(b);

`

**2. Octal Number

If the number starts with 0 and the following digits are smaller than 8. It will be parsed as an Octal Number.

JavaScript `

let x = 0562; console.log(x);

`

**3. Binary Numbers

They start with 0b or 0B followed by 0's and 1's.

JavaScript `

let x = 0b11; let y = 0B0111;

console.log(x); console.log(y);

`

**4. Hexadecimal Numbers

They start with 0x or 0X followed by any digit belonging (0123456789ABCDEF)

JavaScript `

let x = 0xfff; console.log(x);

`

Number Coercion in JavaScript

In JavaScript, **coercion refers to the automatic or implicit conversion of values from one data type to another. When different types of operators are applied to values, JavaScript performs type coercion to ensure that the operation can proceed. Let’s explore some common examples of coercion:

1. Undefined to NaN

When you perform an operation involving **undefined, JavaScript returns **NaN (Not-a-Number).

JavaScript `

const res = undefined + 10; console.log(res); // NaN

`

2. Null to 0

The value **null is **coerced to 0 when used in arithmetic operations.

JavaScript `

const total = null + 5; console.log(total); // 5

`

3. **Boolean to Number

Boolean values (true and false) are converted to numbers****: 1 for true** and 0 for false.

JavaScript `

const n1 = true + 10; const n2 = false + 10;

console.log(n1); console.log(n2);

`

4. **String to Number

When performing arithmetic operations, JavaScript converts strings to numbers. If the string cannot be parsed as a valid number, it returns **NaN.

JavaScript `

const s1 = '42'; const s2 = 'hello';

const strToNum1 = Number(s1); const strToNum2 = Number(s2);

console.log(strToNum1); console.log(strToNum2);

`

**5. BigInts and Symbols

Attempting to coerce **Symbol values to numbers results in a TypeError.

JavaScript `

const symbol = Symbol('mySymbol');

const symToNum = Number(symbol); // TypeError console.log(symToNum);

`

**Output:

TypeError: Cannot convert a Symbol value to a number

**Integer conversion

Some operations such as those which work with an array, string indexes, or date/time expect integers. After performing the coercion if the number is greater than 0 it is returned as the same and if the number NaN or -0, it is returned as 0. The result is always an integer.

**Fixed-width number Conversion

In Javascript, there are some functions that deal with the binary encoding of integers such as bitwise operators and typedArray objects. The bitwise operators always convert the operands to 32-bit integers.

JavaScript Number Methods

Now, we will use Number methods such as toString(), toExponential(), toPrecision(), isInteger(), and toLocaleString() method. Let's see the examples of these Number methods.

JavaScript `

let x = 21 console.log(x.toString()); console.log(x.toExponential()); console.log(x.toPrecision(4)); console.log(Number.isInteger(x)); console.log(x.toLocaleString("bn-BD"));

`

**Output:

21 2.1e+1 21.00 true ২১

**Some Facts About Numbers in JavaScript

We have a complete list of Javascript Number Objects methods, to check those please go through this Javascript Number Complete Reference article.

JavaScript Numbers | Web Development