How Can I Check If A Variable In An Array In An Array In An Array Is Defined And Not Null?

I am trying to check to see if wordDefinitionId is defined and not null. Here's what I have been trying to do but think even this code seems to give some problems. Is there an ea

Solution 1:

Use &&(AND) logical operator between conditions, if first condition fails second condition will not check and so on

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

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].wordDefinitionIddocument.write('<pre>' + JSON.stringify(wos, 0, 3) + '</pre>');

Solution 2:

You don't reach the third if, because in your second if statement, the wos.word.wordForms[0].synonyms will evaluate to true as it is defined and is an empty list. You can check it yourself:

if (wos.word.wordForms[0].synonyms) { alert('Yes!'); } // will alert 'Yes!'

But right next to it, you try to access wos.word.wordForms[0].synonyms[0], which does not exist, hence the TypeError: wos.word.wordForms[0].synonyms[0] is undefined. The same situation is with your wos.word.wordForms[0].sampleSentences

In order to fix this, check the length of the list as well:

if (wos.word.wordForms 
  && wos.word.wordForms[0].synonyms 
  && wos.word.wordForms[0].synonyms.length  // <-- check for element existence
  && wos.word.wordForms[0].synonyms[0].synonymId) {
    ...
}