leetcode-890.js

var findAndReplacePattern = function(words, pattern) {
  const result = []
  for (let i=0; i < words.length; i++) {
    const word = words[i]
    if (matchPattern(word, pattern)){
      result.push(word)
    }
  }
  return result
};

function matchPattern(word, pattern) {
  const charMapping = {}
  const charSet = new Set()
  
  for (let i=0; i < pattern.length; i++) {
    const charPattern = pattern[i]
    const charWord = word[i]
    
    const found = charMapping[charPattern]
    const used = charSet.has(charWord)
    const match = found && found === charWord
    
    if (!found && !used) {
      charMapping[charPattern] = charWord
      charSet.add(charWord)
    } else if (!match || (!found && used)) {
      return false
    }
  }
  return true
}