Returns the index of the first occurrence of a value in a typed array, or -1 if it is not present.
indexOf(value, fromIndex?);
value
The value to locate in the array.
fromIndex optional
The array index at which to begin the search. If fromIndex is omitted, the search starts at index 0.
new BigInt64Array([23, 42, 108]).indexOf(42)
1
new BigInt64Array([23, 42, 108]).indexOf(88)
-1
An index or -1 if the element was not found.