Similarly to all the methods we previously saw, you can also define a starting index where to start check the Array. The difference between the two methods is the same as the one we saw between Array.includes and Array.find, where the first one ( Array.indexOf) will accept a value to check whereas the second one ( Array.findIndex) will accept a callback to perform more advanced checks. These methods are useful because they can be used to both checks if an element exists in the Array while at the same time getting a reference as to where that element is positioned, which we can use to then replace that said element. To check if an element exists, we simply need to check if the returned value is -1 or not.

!!arr.find((a) => a > 2 & a el = 1) != -1Īrray.indexOf and Array.findIndex are similar because they both return the index of the first matching element found in our Array, returning us -1 if it’s not found. It’s a more powerful method compared to Array.includes as we can pass a callback to it, not just a value to check, meaning that we can do more complex checks such as: const arr = This method will return the value itself or undefined if no value is found so we can use the !! operator to convert the result to boolean and quickly see if there’s a match or not.

Let’s continue with more methods: const arr = Īrray.find is also another method we can use to check if our Array contains a certain value. This method can take an additional argument which defines the index from where we want to start looking, leave empty if you want to check the whole Array.

We can do that in different ways such as: const arr = Īrray.includes is probably the easiest method to remember and it will return us true or false if our Array includes or not the value we passed. Learn Now Check that an Array contains a valueįirst, let’s look at different ways of checking if our Array includes a certain value provided.

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