Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the Array that extends from the specified index to the last element. Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the entire Array. Deleted elements are visited as if they were undefined.Searches for an element that matches the conditions defined by a specified predicate, and returns the zero-based index of the first occurrence within an Array or a portion of it.

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.Note, however, that the length of the array is saved before the first invocation of callbackFn. 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.

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. It calls a provided callbackFn function once for each element in an array in ascending-index order, until callbackFn returns a truthy value.

Object.prototype._lookupSetter_() Deprecated.

Object.prototype._lookupGetter_() Deprecated.

Object.prototype._defineSetter_() Deprecated.

Js findindex