# JavaScript Algorithm to Check for a Perfect Square Number

## Checking if a number is a perfect square

By Erica N on Jan 14, 2022

*Photo by Vincent LaVigna on Unsplash*

We are going to write a function called `isSquare`

that will accept an integer `n`

as an argument.

In this function, you will check if a number is a perfect square. A perfect square is an integer that is the square of an integer. In other words, if you were to square root an integer, the result should be another integer. If that's the case, then that integer (the number you square rooted) is a perfect square.

To know whether a number is a perfect square or not, we calculate the square root of the given number. If the result is a whole number then the given number is a perfect square.

If we were to check if `18`

is a perfect square, we would square root that number and get `4.24264068712`

. Since that is not a whole number, we can conclude that `18`

is not a perfect square.

But if we did the same for `16`

and square root that number, we would get `4`

. Since `4`

is a whole number, we know that `16`

is a perfect square.

The goal of the function is to return `true`

if the given value is a perfect square and `false`

if it is not a perfect square.

To begin, we check if the number is positive. Perfect squares can't be negative numbers so if it is a negative number, return `false`

.

```
if (n < 0) {
return false;
}
```

As mentioned above, knowing if a number is a perfect square will depend on the square root of that value. We will use `Math.sqrt()`

to square root the input.

```
Math.sqrt(n)
```

To check if the result is a whole number, we will use `Number.isInteger()`

and use our `Math.sqrt(n)`

as an argument.

```
Number.isInteger(Math.sqrt(n))
```

With that in mind, we can now check if `n`

is a perfect square. If the square root result is a whole number, the function will return `true`

and if not, return `false`

.

```
if (Number.isInteger(Math.sqrt(n))) {
return true;
} else {
return false;
}
```

That's it. Here is the rest of the function:

Thank you for reading.