findIndex.js 1.1 KB

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  1. import _curry2 from "./internal/_curry2.js";
  2. import _dispatchable from "./internal/_dispatchable.js";
  3. import _xfindIndex from "./internal/_xfindIndex.js";
  4. /**
  5. * Returns the index of the first element of the list which matches the
  6. * predicate, or `-1` if no element matches.
  7. *
  8. * Acts as a transducer if a transformer is given in list position.
  9. *
  10. * @func
  11. * @memberOf R
  12. * @since v0.1.1
  13. * @category List
  14. * @sig (a -> Boolean) -> [a] -> Number
  15. * @param {Function} fn The predicate function used to determine if the element is the
  16. * desired one.
  17. * @param {Array} list The array to consider.
  18. * @return {Number} The index of the element found, or `-1`.
  19. * @see R.transduce, R.indexOf
  20. * @example
  21. *
  22. * const xs = [{a: 1}, {a: 2}, {a: 3}];
  23. * R.findIndex(R.propEq('a', 2))(xs); //=> 1
  24. * R.findIndex(R.propEq('a', 4))(xs); //=> -1
  25. */
  26. var findIndex =
  27. /*#__PURE__*/
  28. _curry2(
  29. /*#__PURE__*/
  30. _dispatchable([], _xfindIndex, function findIndex(fn, list) {
  31. var idx = 0;
  32. var len = list.length;
  33. while (idx < len) {
  34. if (fn(list[idx])) {
  35. return idx;
  36. }
  37. idx += 1;
  38. }
  39. return -1;
  40. }));
  41. export default findIndex;