word_search.js

// possible words
var words = ["lazy", "crackers", "hello", "cruel", "world", "bears", "need", "not", "apply"];

// characters
var puzzle = " \
r b f x w \
h e l l o \
o a h c r \
c r u e l \
v s u f d \
";

var solve = function solve(puzzle, words) {
  var results = [],
      puzzle = puzzle.replace(/\s/g, ''),
      lineCount = Math.round(Math.sqrt(puzzle.length)) - 1;
    
  for(var _i = 0, _len = words.length; _i < _len; _i++) {
    var w = words[_i],
        re = '('+w+')|('+w.split('').join('.{'+ lineCount +'}')+')';

    puzzle.match(RegExp(re, 'g')) && results.push(w);
  }
    
  return results;
};

solve(puzzle, words);
//=> ["hello", "cruel", "world", "bears"]