How can I check if a variable in an array in an array in an array is defined and not null?

Question

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 easy way for me to do this check and set the value of wos.wordDefinitionId to either the value (if it exists) or zero if it does not exist.

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
      }
   }
}

Note that if set then I want to get the wordDefinitionId that is in the first array position of wordDefinitions etc.

Update:

I tried the answer suggested:

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

However when I debug the code does not reach the final "if"

Here for reference are the objects:

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}

Same here but maybe easier to see:

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}

possibly change of the data structure?

Nina Scholz
– Nina Scholz

2016-05-18 09:56:45 +00:00
Commented May 18, 2016 at 9:56 — Nina Scholz
– Nina Scholz, Commented May 18, 2016 at 9:56
smells like a recursive approach is required :-)

Jankapunkt
– Jankapunkt

2016-05-18 09:57:50 +00:00
Commented May 18, 2016 at 9:57 — Jankapunkt
– Jankapunkt, Commented May 18, 2016 at 9:57

Pranav C Balan · Accepted Answer · 2016-05-18 10:19:13Z

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].wordDefinitionId

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

edited May 18, 2016 at 10:19

answered May 18, 2016 at 9:56

Pranav C Balan

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5 Comments

Samantha J T Star Over a year ago

I tried this and updated the answer. When I debug every line the code gets as far as the check for synonyms and then no further in the chrome developer tools debugger. So it seems that the if() is causing it to exit. Do you have any ideas what might cause this?

Samantha J T Star Over a year ago

Can you explain what this means. How could I check for this so the code doesn't stop or exit ? I updated the question to show the data so many that helps. Thanks

Samantha J T Star Over a year ago

thanks. Can you add in the three checks that I have so we could see if it gets to end and sets the Ids. I would do this but I am not sure how to edit a code snippet that you created. Thanks

Pranav C Balan Over a year ago

@SamanthaJ : just put an alert or console.log statement inside the if

Samantha J T Star Over a year ago

I tried adding the three condition checks in my own snippet but it doesn't run to the end. Do you think your answer is maybe not accounting for all possibilities?

iulian · Accepted Answer · 2016-05-18 13:14:29Z

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) {
    ...
}

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