javascript - 仅当找到或未找到结果时，如何才能 console.log ？

Question

我正在为学习项目创建一个小型搜索工具，但我不明白为什么这个 console.logs 两次

var states = {
  North_Dakota: {capital: 'Bismarck', region: 'Mid-west'},
  Minnesota: {capital: 'Saint paul', region: 'Mid-west'},
  Montana: {capital: 'Helena', region: 'Mid-west'},
  Wisconsin: {capital: 'Madison', region: 'Mid-west'}
};

var searchCapitals = function(givenWord){
  for (var key in states) {
    if (givenWord.toLowerCase() === key.toLowerCase()) {
      console.log('Search found: ' + key + ' (capital: ' + states[key].capital + ', region: ' + states[key].region + ')')
    } else (givenWord.toLowerCase() != key.toLowerCase()) {
      console.log('No results found.')
    }
  }
};

searchCapitals('wisconsin');

因为“wisconsin”匹配，所以它应该只输出第一次吗？但它会为每个对象项记录字符串“未找到结果”。我们将不胜感激。

Answer 1

不要记录循环，而是尝试在循环中设置一个 bool 值，并记录是否循环了整个对象或数组:

var states = {
  North_Dakota: {capital: 'Bismarck', region: 'Mid-west'},
  Wisconsin: {capital: 'Madison', region: 'Mid-west'},
  Minnesota: {capital: 'Saint paul', region: 'Mid-west'},
  Montana: {capital: 'Helena', region: 'Mid-west'}
};

var searchCapitals = function(givenWord){
  var found = false;
  var foundKey = "";
  
  for (var key in states) {
      
      console.log(key);
    if (givenWord.toLowerCase() === key.toLowerCase()) {
      found = true;
      foundKey = key;
      break; // stop searching if you found a matching pair
    }
  }
      
  if(found)
    console.log('Search found: ' + foundKey + ' (capital: ' + states[foundKey].capital + ', region: ' + states[foundKey].region + ')')
  else
    console.log('No results found.')
};

searchCapitals('wisconsin');