loading...

JavaScript Numbers

ziizium profile image Habdul Hazeez ・3 min read

Programmer or not, am pretty sure you've encountered numbers before. I mean, numbers are everywhere from economics to physics and even in nature.

It is quiet easy to get started with numbers in JavaScript but, before long you'll come to the fact that numbers in JavaScript can be really weird . If you are familiar with the behavior of numbers in some programming languages this won't come as a surprise to you.

All screenshots are from Firefox 71.0 and its Developer Tools. One particular feature in Firefox 71.0 that's worthy of mention is the multi-line code editor in the console.


Every computation performed by a computer program will involve numbers directly or indirectly. Directly, if you are doing some calculations and indirectly, because all high level programming code are converted to machine code which are numbers (0's and 1's).

You might not deal with number's often but it is an huge advantage if you know how they work in JavaScript most especially floating point numbers.

JavaScript represents numbers using the 64-bit floating-point format defined by the IEEE 754 standard. Which means it can represent numbers as large as ±1.7976931348623157 × 10308 and as small as ±5 × 10−324.

When a number appears directly in a JavaScript program, it’s called a numeric literal.

Just like regular math, you can perform calculations in JavaScript using popular math operators like +, - , / and % (modulus).

Lets play with some code.

// addition
console.log(1 + 1);

// multiplication
console.log(2 * 3);

// division
console.log(4 / 2);

// modulus or remainder
console.log(2 % 2);

// exponential operator introduced in
// EcmaScript 2016 (ES7)
console.log(2 ** 2);

// exponential calculation using the Math.pow()
// function, this is similar to the ** (exponential operator)
// introduced in EcmaScript 2016 (ES7)
console.log(Math.pow(2,2));

The code when executed in the console:

Numbers in JavaScript

The code examples above are example of numeric literals.

Now, let's have a look at floating point numbers.

/**
  * Basic calculation with floating point numbers
  */

// addition
console.log(0.1 + 1.2);

// multiplication
console.log(2.2 * 3.12);

// division
console.log(4.1 / 2.08);

// modulus or remainder
console.log(2.0 % 1.2);

// exponential operator introduced in
// EcmaScript 2016 (ES7)
console.log(2.2 ** 2);

// exponential calculation using the Math.pow()
// function, this is similar to the ** (exponential operator)
// introduced in EcmaScript 2016 (ES7)
console.log(Math.pow(0.2,2));

The code when executed in the console:

Numbers in JavaScript

I mentioned earlier that JavaScript numbers are weird, well it has to do with calculations and comparisons involving floating point numbers. Take a look at the following example.

0.1 + 0.1 == 0.2;

// Expected output: true

When executed in the console:

Numbers in JavaScript

The next calculation might surprise you.

0.1 + 0.2 == 0.3

// Expected output: ?

When executed in the console:

Numbers in JavaScript

Why is this? Well that's because numbers in JavaScript are defined by the IEEE 754 standard.

The last code execution evaluated to false because 0.1 + 0.2 is actually 0.30000000000000004 not 0.3. You can confirm this in the console.

Numbers in JavaScript

Yeah, i know this is weird. There is even a website dedicated to this specific number 0.30000000000000004. The website is https://0.30000000000000004.com.

You can visit the site for more information about floating point numbers.

Numbers can be made negative by adding a negative sign (-) before the number.

Negative numbers in JavaScript

Division by zero is not an error in JavaScript it simply returns Infinity or negative infinity (-Infinity).

2/0

// Expected output: infinity

When executed in the console:

Numbers in JavaScript

There is one exception however, zero divided by zero does not have a well-defined value and the result of this operation is the special not-a-number value, printed as NaN.

0/0

// Expected output: NaN

When executed in the console:

Numbers in JavaScript

NaN also arises if you attempt to divide Infinity by Infinity or take the square root of a negative number or use arithmetic operators with non-numeric operands that cannot be converted to numbers.

There are also hexadecimal numbers and octal numbers in JavaScript. They are not included in this post for the sake of simplicity.

Up next, Loops.

Posted on by:

ziizium profile

Habdul Hazeez

@ziizium

I teach and write code with interests in Web Development, Computer Security, and Artificial Intelligence.

Discussion

pic
Editor guide