# JavaScript: Check a number is prime or not

## JavaScript Function: Exercise-8 with Solution

Write a JavaScript function that accepts a number as a parameter and check the number is prime or not.

Note : A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.

Pictorial Presentation: Sample Solution: -

HTML Code:

``````<!DOCTYPE html>
<html>
<meta charset=utf-8 />
<title>Check a number is prime or not</title>
<body>

</body>
</html>
```
```

JavaScript Code:

``````function test_prime(n)
{

if (n===1)
{
return false;
}
else if(n === 2)
{
return true;
}else
{
for(var x = 2; x < n; x++)
{
if(n % x === 0)
{
return false;
}
}
return true;
}
}

console.log(test_prime(37));
```
```

Sample Output:

```true
```

Flowchart: Live Demo:

See the Pen JavaScript -Counts the number of vowels within a string-function-ex- 7 by w3resource (@w3resource) on CodePen.

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## JavaScript: Tips of the Day

Shorten an array using its length property

A great way of shortening an array is by redefining its length property.

```let array = [0, 1, 2, 3, 4, 5, 6, 6, 8, 9]
array.length = 4
// Result: [0, 1, 2, 3]
```

Important to know though is that this is a destructive way of changing the array. This means you lose all the other values that used to be in the array.

Ref: https://bit.ly/2LBj213