findLastIndex.js•1.19 kB
var _curry2 = require('./internal/_curry2');
var _dispatchable = require('./internal/_dispatchable');
var _xfindLastIndex = require('./internal/_xfindLastIndex');
/**
* Returns the index of the last element of the list which matches the
* predicate, or `-1` if no element matches.
*
* Dispatches to the `findLastIndex` method of the second argument, if present.
*
* Acts as a transducer if a transformer is given in list position.
*
* @func
* @memberOf R
* @since v0.1.1
* @category List
* @sig (a -> Boolean) -> [a] -> Number
* @param {Function} fn The predicate function used to determine if the element is the
* desired one.
* @param {Array} list The array to consider.
* @return {Number} The index of the element found, or `-1`.
* @see R.transduce
* @example
*
* var xs = [{a: 1, b: 0}, {a:1, b: 1}];
* R.findLastIndex(R.propEq('a', 1))(xs); //=> 1
* R.findLastIndex(R.propEq('a', 4))(xs); //=> -1
*/
module.exports = _curry2(_dispatchable('findLastIndex', _xfindLastIndex, function findLastIndex(fn, list) {
var idx = list.length - 1;
while (idx >= 0) {
if (fn(list[idx])) {
return idx;
}
idx -= 1;
}
return -1;
}));