In JavaScript, 'this' keyword refers to the object it belongs to. If it is empty, the value 'undefined' will be passed as its 'this' value. It is an optional argument that is passed to the function and used as its 'this' value. arr: This is the array that the findIndex() was called upon. Index: Indicates the index of the current element being processed. The testFunc() is a function that is used to execute a condition on each element of the array until the function returns true, indicating that the element satisfying the condition was found.ĬurrentValue: This indicates the current element in the array being processed. The above findIndex() method takes two arguments: The syntax of the findIndex() method is as follows findIndex(testfunc(currentValue, index, arr), thisValue) If no element of the array satisfies the testing condition, it returns -1. The findIndex() method returns the index of the first element in array that satisfies the given testing function. The prototype constructor allows you to add new properties and methods to the Array() object. This method was added to the array.prototype() in the JavaScript ES6.

Today, let us understand how the findIndex() method works. JavaScript methods are actions that can be performed on objects.

Findindex javascript