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 puzzle_lines_array = [],
      puzzle_lines = [],
      puzzle_array = [],
      found_words = [],
      row = 0,
      column = -1,
      line = '',
      f_find_letter = _.memoize(function(letter) {
          var coords = false;
    
          _.each(puzzle_lines_array, function(e, y) {
              _.each(e, function(f, x) {
                  if(!coords) {
                      coords = [];
                  }
            
                  if(letter == f) {
                      coords.push({'x': x, 'y': y});
                  }
              });
          });
    
          return coords;
      }),
      f_letter_at = function(x, y) {
          return puzzle_lines_array[y][x];
      };
    
    //Split the string in lines
    _.each(puzzle, function(e) {
        if(e != " ") {
            if(column == 4) {
                puzzle_lines.push(line);
                line = e;
                column = 0;
                row++;
            }
            else if(column == 3 && row == 4) {
                puzzle_lines.push(line + e);
            }
            else {
                line = line + e;
                column++;
            }
        }
    });
    // console.log(puzzle_lines);
    
    //Split the lines in arrays
    _.each(puzzle_lines, function(e, i) {
        puzzle_lines_array.push(e.split(''));
    });
    
    // console.log(puzzle_lines_array);
    
    //Loop through possible words
    _.each(words, function(e) {
        var word = e,
            first = _.first(e),
            last = _.last(e),
            first_coords = f_find_letter(first);
        
        //Get positions of first letter
        _.each(first_coords, function(f) {
            if(f.x + word.length <= 5) {
                //Enough space for word horizontally
                //Loop through word letter to see if match
                for(var _i = 0, _len = word.length; _i < _len; _i++) {
                    var _x = _i + f.x,
                        _y = f.y;
                    
                    if(f_letter_at(_x, _y) != word[_i]) {
                        break;
                    }
                    else if(_i + 1 == _len) { // last word
                        found_words.push(word);
                    }
                }
            }
            
            if(f.y + word.length <= 5) {
                //Enough space for word vertically
                //Loop through word letter to see if match
                for(var _i = 0, _len = word.length; _i < _len; _i++) {
                    var _x = f.x,
                        _y = _i + f.y;
                    
                    if(f_letter_at(_x, _y) != word[_i]) {
                        break;
                    }
                    else if(_i + 1 == _len) { // last word
                        found_words.push(word);
                    }
                }
            }
        });
    });
    return found_words;
};

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