FrontEnd Development Zero to Hero (67 Part Series)

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 × 10`

and as small as ^{308}`±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:

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:

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:

The next calculation might surprise you.

```
0.1 + 0.2 == 0.3
// Expected output: ?
```

When executed in the console:

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.

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.

**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:

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:

`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.

FrontEnd Development Zero to Hero (67 Part Series)

Posted on by:

### Habdul Hazeez

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

## Discussion