Forehead slapper after code challenge

Duh.js

'use strict';

var input = [
    '[[({}{})]{}]',
    '][(}))(}})]',
    '[(){}]',
    ']()',
    '{([]{})()}'
  ]
  , output = [1, 0, 1, 0, 1 ]
  ;

function isValid (arr) {

  var reduce = function (str) {
    var s = str;
    s = s.replace(/\{\}/g, '');
    s = s.replace(/\[\]/g, '');
    s = s.replace(/\(\)/g, '');
    return s;
  };

  var i, output = [];

  var before
    , after
    , last
    ;

  for (i in arr) {

    last = arr[i];

    do {

      before = last;
      after = reduce(before);
      last = after;

    } while (before !== after);

    output.push(after.length > 0);
  }

  return output;
}

console.log(output);