![]() Deleted elements are visited as if they were undefined. If an existing, yet-unvisited element of the array is changed by callbackFn, its value passed to the callbackFn will be the value at the time that element gets visited.Changes to already-visited indexes do not cause callbackFn to be invoked on them again.callbackFn will not visit any elements added beyond the array's initial length when the call to findIndex() began. Javascript find index of an array that contains object.Note, however, that the length of the array is saved before the first invocation of callbackFn. findIndex (array, predicate, context) findIndex method return the first index of element in array using predicate function applied on each element. ![]() Empty slots in sparse arrays behave the same as undefined.įindIndex() does not mutate the array on which it is called, but the function provided as callbackFn can. Underscore.JS - findIndex method Previous Page Next Page Syntax. If callbackFn never returns a truthy value, findIndex() returns -1.ĬallbackFn is invoked for every index of the array, not just those with assigned values. findIndex() then returns the index of that element and stops iterating through the array. The findIndex() method returns the index of the first element in an array that pass a test (provided as a function). It calls a provided callbackFn function once for each element in an array in ascending-index order, until callbackFn returns a truthy value. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview Questions.
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