Learn about the Array findIndex method in JavaScript

Find an item in an array with the ‘findIndex’ method in JavaScript.

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The findIndex() method returns the index of the first element of the array if the callback function passed to the findIndex method returns true, otherwise returns -1


  • callback function → A function to execute on each value in the array until the function returns true, indicating that the satisfying element was found.
  • thisArg → Optional object to use as this when executing callback.

The callback function takes three arguments

  • element → current processing element
  • index (Optional)→ index of the element processing
  • array (Optional)→ array in which findIndex method called.


  • once the callback returns the index, it will not process the remaining elements.

Unlike other array methods such as Array.some(), callback is run even for indexes with unassigned values.

Extras :

The Array.find() method, which returns the value of an array element, instead of its index.

You can find the implementation details of findIndex method here.

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