## Find Odd Numbers In An Array In JavaScript

To find odd numbers in an array in JavaScript –

1. Use the filter() method, passing it a function.
2. In each iteration, check if the current number is not divisible by 2, if it isn’t, then it must be an odd number so return true.
3. The filter() method will return a new array with all the odd numbers only.

Let’s discuss this method in detail below.

Contents

## Find Odd Numbers In An Array In JavaScript

The Array.filter() method can be used to filter through an array and only return the elements that pass a certain condition. In this case, we want to find all of the odd numbers in our array.

To do this, we need to pass a callback function into the filter method. This callback function should take in a single parameter, which will represent each element in the array that we are filtering.

We can then use this callback function to check if the current number is an odd number or not. If it is, then we return true, else we return false.

The filter() method will only keep those elements in our original array that return true from the callback function.

Here is the code that we would use to find odd numbers in an array in JavaScript:

``````var arr = [-2, -1, 0, 1, 2];

function isOdd(num) {

return num % 2 !== 0;

}

var oddNumbers = arr.filter(isOdd);

console.log(oddNumbers); // [-1, 1]``````

In the code above, we have an array of numbers called arr. We also have a function called isOdd() which takes in a single parameter num and returns true if num is an odd number.

If num is not an odd number, then it returns false.

We use this function as our callback function for the filter() method. This means that, in each iteration, the isOdd() function will be called with the current element as its parameter.

If isOdd() returns true, then the element will be kept in the new array that is returned by the filter() method. Otherwise, it will be excluded from the new array.

So, in the end, oddNumbers will contain all of the odd numbers from our original array.

As you can see, using the filter() method is a very convenient way to find all of the odd numbers in an array in JavaScript.

Another method that you can use is the forEach() method. This method is used to execute a callback function on each element in an array.

You can use the forEach() method to find odd numbers in an array in JavaScript. The code would look like this:

``````var arr = [-2, -1, 0, 1, 2];

var oddNumbers = [];

arr.forEach(function(num) {

if (num % 2 !== 0) {

oddNumbers.push(num);

}

});

console.log(oddNumbers); // [-1, 1]``````

In the code above, we have an array called arr. We also have an empty array called oddNumbers.

We use the forEach() method to loop through each element in the arr array. In each iteration, we check if the current number is an odd number or not.

If it is, then we add it to our oddNumbers array.

So, in the end, oddNumbers will contain all of the odd numbers from our original array.

You can also use a for loop to find all of the odd numbers in an array. The code would look like this:

``````var arr = [-2, -1, 0, 1, 2];

var oddNumbers = [];

for (var i = 0; i < arr.length; i++) {

if (arr[i]% 2 !== 0) {

oddNumbers.push(arr[i]);

}

}

console.log(oddNumbers); // [-1, 1]``````

In the code above, we have an array called arr. We also have an empty array called oddNumbers.

We use a for loop to loop through each element in the arr array. In each iteration, we check if the current number is an odd number or not.

If it is, then we add it to our oddNumbers array.

So, in the end, oddNumbers will contain all of the odd numbers from our original array.

You can also use the Array.reduce() method to find all of the odd numbers in an array. The code would look like this:

``````var arr = [-2, -1, 0, 1, 2];

var oddNumbers = arr.reduce(function(accumulator, currentValue) {

if (currentValue % 2 !== 0) {

accumulator.push(currentValue);

}

return accumulator;

}, []);

console.log(oddNumbers); // [-1, 1]``````

In the code above, we have an array called arr. We also have an empty array called oddNumbers.

We use the Array.reduce() method to loop through each element in the arr array. In each iteration, we check if the current number is an odd number or not.

If it is, then we add it to our oddNumbers array.

So, in the end, oddNumbers will contain all of the odd numbers from our original array.

As you can see, there are many different ways that you can find odd numbers in an array in JavaScript.

Which method you choose to use will depend on your needs and preferences.

Whichever method you choose, the end result will be the same.