dart:collection

lastIndexOf method

int lastIndexOf(Object element, [ int startIndex ])

Returns the last index in the list a of the given element, starting the search at index startIndex to 0. Returns -1 if element is not found.

Source

int lastIndexOf(Object element, [int startIndex]) {
  if (startIndex == null) {
    startIndex = this.length - 1;
  } else {
    if (startIndex < 0) {
      return -1;
    }
    if (startIndex >= this.length) {
      startIndex = this.length - 1;
    }
  }
  for (int i = startIndex; i >= 0; i--) {
    if (this[i] == element) {
      return i;
    }
  }
  return -1;
}