How to output a specific object in Node.js but don't output those that do not exist?

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You use a guard, e.g. `var grade = obj[i].Statistics && obj[i].Statistics[i] && obj[i].Statistics[i].Grade;`. There has to be a good dupetarget to point this at, I'll see if I can find one. — T.J. Crowder, Jul 07 '19 at 12:56
Related: https://stackoverflow.com/questions/6970346/what-is-x-foo — T.J. Crowder, Jul 07 '19 at 12:57
Beside that error, there are other problems like returning from the loop and using `i` as the index for the inner array. — Titus, Jul 07 '19 at 13:00
I tried putting the output code outside the loop but it doesn't seem to fix it either — , Jul 07 '19 at 13:02

Code Maniac · Accepted Answer · 2019-07-07T13:02:25.783

You need to check for existence of Statistics first before accessing it,

change this

 var grade = obj[i].Statistics[i].Grade;
 var hasPassOrFail = obj[i].Statistics[i].Status;

to this

  var grade = obj[i] && obj[i].Statistics && obj[i].Statistics[0] && obj[i].Statistics[0].Grade;
  var hasPassOrFail = obj[i] && obj[i].Statistics && obj[i].Statistics[0] && obj[i].Statistics[0].Status;

var obj = JSON.parse('[{"Name":"Student1","Id":44844541,"Statistics":[{"Grade":6,"Status":"Pass"}]},{"Name":"Student2","Id":48484848},{"Name":"Student3","Id":99999989,"Statistics":[{"Grade":2,"Status":"Fail"}]}]')

for (var i = 0, len = obj.length; i < len; i++) {

  var grade = obj[i] && obj[i].Statistics && obj[i].Statistics[0] && obj[i].Statistics[0].Grade;
  var hasPassOrFail = obj[i] && obj[i].Statistics && obj[i].Statistics[0] && obj[i].Statistics[0].Status;

  if (grade || hasPassOrFail){
   console.log(grade,hasPassOrFail)
  }
}

How to output a specific object in Node.js but don't output those that do not exist?

1 Answers1