Question

我正在尝试检查wordDefinitionId是否已定义，而不是null。这是我一直试图做的事情，但想想即使这段代码似乎也会出现一些问题。我是否有一种简单的方法可以执行此检查并将wos.wordDefinitionId的值设置为值（如果存在）或零（如果不存在）。

if (wos.word.wordForms) {
   if (wos.word.wordForms[0].wordDefinitions) {
      if (wos.word.wordForms[0].wordDefinitions[0].wordDefinitionId)
         wos.wordDefinitionId = wos.word.wordForms[0].wordDefinitions[0].wordDefinitionId
      }
   }
}

请注意，如果设置，那么我想得到wordDefinitions，它位于wordDefinitions等的第一个数组位置。

更新

我尝试了建议的答案：

if (wos.word.wordForms && wos.word.wordForms[0].wordDefinitions && wos.word.wordForms[0].wordDefinitions[0].wordDefinitionId)
    wos.wordDefinitionId = wos.word.wordForms[0].wordDefinitions[0].wordDefinitionId;
if (wos.word.wordForms && wos.word.wordForms[0].synonyms && wos.word.wordForms[0].synonyms[0].synonymId)
    wos.synonymId = wos.word.wordForms[0].synonyms[0].synonymId

// When I debug the code does not reach the next line. 

if (wos.word.wordForms && wos.word.wordForms[0].sampleSentences && wos.word.wordForms[0].sampleSentences[0].sampleSentenceId)
    wos.sampleSentenceId = wos.word.wordForms[0].sampleSentences[0].sampleSentenceId

然而，当我调试代码时没有到达最终＆＃34;如果＆＃34;

此处供参考：

console.log(JSON.stringify(wos.word))
VM6085:1 {"wordId":"tyyyyyy","wordIdentity":160,"ascii":116,"categoryId":1,"groupId":1,"lessonId":1,"ielts":null,"toefl":true,"toeic":null,"wordForms":[{"wordFormId":"qwqwqwqwq","wordFormIdentity":145,"ascii":113,"wordId":"tyyyyyy","primary":false,"posId":1,"sampleSentences":[],"synonyms":[],"wordDefinitions":[{"wordDefinitionId":142,"wordFormId":"qwqwqwqwq","text":"wrwrwrwrwr","ascii":119}],"pos":null,"version":"AAAAAAAADn0=","createdBy":2,"createdDate":"2016-05-03T13:23Z","modifiedBy":2,"modifiedDate":"2016-05-03T20:23Z"}],"lesson":null,"wordCategory":null,"wordGroup":null,"version":"AAAAAAAADf4=","createdBy":2,"createdDate":"2016-05-03T13:23Z","modifiedBy":2,"modifiedDate":"2016-05-03T20:23Z","current":true}

同样在这里，但也许更容易看到：

的console.log（JSON.stringify（wos.word）） VM6085：1 {＆＃34; wordId＆＃34;：＆＃34; tyyyyyy＆＃34;，＆＃34; wordIdentity＆＃34;：160，＆＃34; ascii＆＃34;：116，＆＃34; categoryId＆＃ 34;：1，＆＃34;的groupId＆＃34;：1，＆＃34; lessonId＆＃34;：1，＆＃34; IELTS＆＃34;：空，＆＃34; TOEFL＆＃34;：真，＆＃34; TOEIC＆＃34;：空，＆＃34;词形等＆＃34;：[{＆＃34; wordFormId＆＃34;：＆＃34; qwqwqwqwq＆＃34;＆＃34; wordFormIdentity＆＃34;：145，＆＃34; ASCII＆＃34; 113＆＃34;的wordID＆＃34;：＆＃34; tyyyyyy＆＃34;＆＃34;主＆＃34;：假，＆＃34; posId＆＃34;：1 ＆＃34; sampleSentences＆＃34;：[]，＆＃34;同义词＆＃34;：[]，＆＃34; wordDefinitions＆＃34;：[{＆＃34; wordDefinitionId＆＃34; 142＆＃34 ; wordFormId＆＃34;：＆＃34; qwqwqwqwq＆＃34;＆＃34;文本＆＃34;：＆＃34; wrwrwrwrwr＆＃34;＆＃34; ASCII＆＃34; 119}]，＆＃34; POS＆＃34;：空，＆＃34;版本＆＃34;：＆＃34; AAAAAAAADn0 =＆＃34;＆＃34; createdBy＆＃34;：2＆＃34; createdDate＆＃34;：＆＃34 ; 2016-05-03T13：23Z＆＃34;＆＃34; modifiedBy＆＃34;：2＆＃34; modifiedDate＆＃34;：＆＃34; 2016-05-03T20：23Z＆＃34;}]，＆＃34;教训＆＃34;：空，＆＃34; wordCategory＆＃34;：空，＆＃34; wordGroup＆＃34;：空，＆＃34;版本＆＃34;：＆＃34; AAAAAAAADf4 =＆＃34 ;，＆＃34; createdBy＆＃34;：2＆＃34; createdDate＆＃34;：＆＃34; 2016-05- 03T13：23Z＆＃34;＆＃34; modifiedBy＆＃34;：2＆＃34; modifiedDate＆＃34;：＆＃34; 2016-05-03T20：23Z＆＃34;＆＃34;电流＆＃34; ：真}

Answer 1

在条件之间使用&&(AND) logical operator，如果第一个条件失败，则第二个条件不会检查，等等

if (wos.word.wordForms && wos.word.wordForms[0].wordDefinitions && wos.word.wordForms[0].wordDefinitions[0].wordDefinitionId)
  wos.wordDefinitionId = wos.word.wordForms[0].wordDefinitions[0].wordDefinitionId

＆＃13;

var wos = {
  word: {
    "wordId": "tyyyyyy",
    "wordIdentity": 160,
    "ascii": 116,
    "categoryId": 1,
    "groupId": 1,
    "lessonId": 1,
    "ielts": null,
    "toefl": true,
    "toeic": null,
    "wordForms": [{
      "wordFormId": "qwqwqwqwq",
      "wordFormIdentity": 145,
      "ascii": 113,
      "wordId": "tyyyyyy",
      "primary": false,
      "posId": 1,
      "sampleSentences": [],
      "synonyms": [],
      "wordDefinitions": [{
        "wordDefinitionId": 142,
        "wordFormId": "qwqwqwqwq",
        "text": "wrwrwrwrwr",
        "ascii": 119
      }],
      "pos": null,
      "version": "AAAAAAAADn0=",
      "createdBy": 2,
      "createdDate": "2016-05-03T13:23Z",
      "modifiedBy": 2,
      "modifiedDate": "2016-05-03T20:23Z"
    }],
    "lesson": null,
    "wordCategory": null,
    "wordGroup": null,
    "version": "AAAAAAAADf4=",
    "createdBy": 2,
    "createdDate": "2016-05-03T13:23Z",
    "modifiedBy": 2,
    "modifiedDate": "2016-05-03T20:23Z",
    "current": true
  }
};



if (wos.word.wordForms && wos.word.wordForms[0].wordDefinitions && wos.word.wordForms[0].wordDefinitions[0].wordDefinitionId)
  wos.wordDefinitionId = wos.word.wordForms[0].wordDefinitions[0].wordDefinitionId

document.write('<pre>' + JSON.stringify(wos, 0, 3) + '</pre>');

＆＃13;

Answer 2

如果您没有达到第三个，因为在您的第二个subset1<-function(id){df2<-df[df$ID==id,]}语句中，if将在定义时评估为true，并且是一个空列表。你可以自己检查一下：

wos.word.wordForms[0].synonyms

但紧接着它，您尝试访问不存在的if (wos.word.wordForms[0].synonyms) { alert('Yes!'); } // will alert 'Yes!'，因此wos.word.wordForms[0].synonyms[0]。您的TypeError: wos.word.wordForms[0].synonyms[0] is undefined

也是如此

为了解决这个问题，请检查列表的长度：

wos.word.wordForms[0].sampleSentences

如何检查数组中数组中数组中的变量是否已定义且不为null？

2 个答案: