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JavaScript Quiz – array filter method can filter odd value

JavaScript Quiz – array filter method can filter odd value

Array filter method –

JavaScript array filter method (Array.forEach()) is used to filter a array element based on condition and create new array with filtered element.

It’s syntax looks like –

let newArray = arr.filter(callback(element[, index, [array]])[, thisArg])

For more detail on JavaScript Array Filter Method click here.

JavaScript Question

In this javascript quiz code, you need to find out does array filter method can filter odd value from a given number element array.

First we declare a variable array using let keyword and assign an javascript array to it. Which contain only number element.

let array = [1, 2, 3, 4, 5];

Now, create another variable newArray using let and assign an array return from the array filter method.

let newArray = array.filter((el) => { … }) ;

But we also pass a condition to filter method which decide which element should be remove from array variable.

((el) => el%2 ) ;

Finally, we are checking the console log for newArray variable. Any idea what is the output.

Answer – [1, 3, 5]

Click To Run Code


Now, you know the answer is [1, 2, 3]. But how it’s working. Let me explain

So, as we can see that we pass a condition to filter method but what it return we do not know.

Let’s deep dive into it. we use el%2 but what is %. So, it’s called Modulus (Remainder). The modulus operator (%) returns the division remainder.

As we are using with value 2. So every element get pass through it and return a remainder based on el value.

But as we can see in array, number element 2 & 4 is the only one give remainder 0.

And 0 is a falsy value which returns false to filter condition due to which they are not included in newArray.

That way, we can remove even value from array and filter out only odd value.

At last, That’s why we get an answer “[1, 3, 5]“.

I hope you understand the concept and logic behind it.

But wait, i have something more for you –

Check out our other javascript quiz – 

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