diff stuff

lcs.js

function createMatrix(m, n) {
  var res = []
  for (var i = 0; i < m; i++){
    var row = []
    for (var j = 0; j < n; j++) {
      row.push({
        length: 0,
        sequences: []
      })
    }
    res.push(row)
  }
  return res
}
function copySequences(source, dest) {
  for(var i = 0; i < source.length; i++) {
    var copy = []
    for (var j = 0; j < source[i].length; j++) {
      copy.push(source[i][j])
    }
    dest.push(copy)
  }
}
function longestCommonSubsequence(str1, str2) {
  var str1List = str1.split('')
  var str2List = str2.split('')
  var matrix = createMatrix(str1List.length + 1, str2List.length + 1)
  for (var i = 0; i < str1List.length; i++) {
    for (var j = 0; j < str2List.length; j++) {
      if (str1List[i] === str2List[j]) {
        matrix[i + 1][j + 1].length = 1 + matrix[i][j].length
        if (matrix[i][j].sequences.length > 0) {
          copySequences(matrix[i][j].sequences, matrix[i + 1][j + 1].sequences)
        } else {
          matrix[i + 1][j + 1].sequences.push([])
        }
        for (var k = 0; k < matrix[i + 1][j + 1].sequences.length; k++) {
          matrix[i + 1][j + 1].sequences[k].push(str1List[i])
        }
        continue
      }
      if (matrix[i][j + 1].length > matrix[i + 1][j].length) {
        matrix[i + 1][j + 1].length = matrix[i][j + 1].length
        copySequences(matrix[i][j + 1].sequences, matrix[i + 1][j + 1].sequences)
        continue
      }
      if (matrix[i][j + 1].length < matrix[i + 1][j].length) {
        copySequences(matrix[i + 1][j].sequences, matrix[i + 1][j + 1].sequences)
        matrix[i + 1][j + 1].length = matrix[i + 1][j].length
        continue
      }
      copySequences(matrix[i][j + 1].sequences, matrix[i + 1][j + 1].sequences)
      copySequences(matrix[i + 1][j].sequences, matrix[i + 1][j + 1].sequences)
      matrix[i + 1][j + 1].length = matrix[i][j + 1].length
    }
  }
  return matrix[str1List.length][str2List.length]
}
function diff(s1, s2) {
var lcs = longestCommonSubsequence(s1, s2)
  if (lcs.sequences.length === 0) {
    return [s1, s2]
  }
  var res1 = ''
  var res2 = ''
  var index = 0
  var i = 0
  var sequence = lcs.sequences[0]
  for (i = 0; i < s1.length; i++) {
    if (sequence[index] === s1[i]) {
      if (++index === sequence.length) {
        res1 += s1.slice(i + 1)
        break
      }
    } else {
      res1 += s1[i]
    }
  }
  index = 0
  for (i = 0; i < s2.length; i++) {
	  if (sequence[index] === s2[i]) {     
      if (++index === sequence.length) {
      	res2 += s2.slice(i + 1)
        break
      }
    } else {
      res2 += s2[i]
    }
  }
  return [res1, res2]
}
console.log(diff('asdfasdf','asf'))