CODEWITHSUNDEEP
javascriptjquery
ashwin karki
ashwin karki

Reputation: 673

Comparing problem with If else statement in Javascript

I have two condition of my same JSON data:

{  
   "selectionId":124,
   "selectionDate":"2070-01-01",
   "selectionAudit":null,
   "letter":[  
      {  
         "letterNo":13,
         "letterId":1,
         "inout":"out",
         "inoutNo":"12332466544",
         "inoutDate":"2070-01-01",
         "letterIssuedSubBy":null,
         "letterFile":null,
         "representativeName":null,
         "representativeNameEng":null,
         "selectionId":124,
         "assessmentNo":null,
         "entryBy":"user98",
         "rStatus":"I",
         "others":null,
         "signatary":"qwerrt",
         "letterBox":null,
         "imageFile":null,
         "imageTitle":null,
         "reminderYesNo":"N"
      }
   ]
}

Same JSON with letter array empty structure :

  {  
       "selectionId":124,
       "selectionDate":"2070-01-01",
       "selectionAudit":null,
       "letter":[]
    }

All these values are stored in var trDataSecondTable; . I tried to compare if the letter is empty or not by using if condition:

  if(trDataSecondTable.letter != null) {
            console.log("asasfasdfdsfdsfds");
         $("#inoutDate").val(trDataSecondTable.letter[0].inoutDate);
         $("#inoutNo").val(trDataSecondTable.letter[0].inoutNo);
         $("#signatary").val(trDataSecondTable.letter[0].signatary);
     }
     else
     {
         console.log("entered in else part");
     }

Though "letter":[] is empty it is not entering into else part. While comparing i also tried trDataSecondTable.letter.length != 0 but also it is not entering into else part.

Upvotes: 0

Views: 70

Answers (3)

jo_va
jo_va

Reputation: 13964

Your condition should check for both null and the length:

if (trDataSecondTable.letter != null && trDataSecondTable.letter.length > 0)

Is is important to check for null before accessing the length property as it guarantees you won't try to access the length property on null, which would raise an exception. This is important since data is rarely reliable.

Because of the && operator, if the first check fails, the second check won't be evaluated.

Actually, an even safer way would be to check if the value is truthy, as this will work for null and undefined:

if (trDataSecondTable.letter && trDataSecondTable.letter.length > 0)

Upvotes: 4

Nicolae Maties
Nicolae Maties

Reputation: 2655

I think this condition is enough

if(trDataSecondTable.letter.length)

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386560

You could check the length of the array.

if (trDataSecondTable.letter.length) {
    // letter has some elements
} else {
    // no elements
}

Upvotes: 1

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