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Javascript – How to check for an item not in an object

I have some borrowed code I’m trying to tweak for my needs. Ref. below code:

// Object that will contain all of the MRNs we want to keep
var assgnAuthToKeep = {};

for each(pid3 in PIDsegment['PID.3']) {
  if (pid3['PID.3.4'].toString() in assgnAuthToKeep) {
    delete PIDsegment[pid3.childIndex];
  }
}

How can I check for the value NOT IN the object in the if statement?
!in doesn’t work nor does not in

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3

Answers


  1. 0

    Like how Rogue mentioned you can invert the boolean expression. Here is your block of code using that method instead:

    var assgnAuthToKeep = {};

for each(pid3 in PIDsegment['PID.3']) {
    let pid3 = PIDsegment['PID.3'][i];
    let pid34Value = pid3['PID.3.4'].toString();

    if (!(pid34Value in assgnAuthToKeep)) {
        delete PIDsegment[pid3.childIndex];
    }
}
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  2. 0

    The !in operator is a valid way to check if a value is not in an object. However, the syntax in your code is incorrect. You need to use the ! operator before the in operator, not after.

    var assgnAuthToKeep = {};

for ( var pid3 in PIDsegment['PID.3'] )

{
    
if ( ! ( pid3['PID.3.4'].toString() in assgnAuthToKeep ) )

 {
       
 delete PIDsegment[pid3.childIndex];

    
}

}
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  3. 0

    I have a few questions:

    • What do your data structures look like?
      • What does PIDsegment look like?
      • Is assgnAuthToKeep a Set, a Map, or an Object?
    • I am not sure what the point of the childIndex is.

    From what I can infer, it looks like you want to use for..of instead of for..in, if you want to access a key on a value.

    // Object that will contain all of the MRNs we want to keep
var assgnAuthToKeep = new Set(['FOO', 'BAR']);

const PIDsegment = {
  'PID.3': [
    { 'PID.3.4': 'FOO', childIndex: 0 },
    { 'PID.3.4': 'BAR', childIndex: 1 },
    { 'PID.3.4': 'BAZ', childIndex: 2 },
  ]
};

for (let pid3 of PIDsegment['PID.3']) {
  const assgnAuth = pid3['PID.3.4']?.toString();
  if (assgnAuthToKeep.has(assgnAuth)) continue;
  console.log('Removing:', assgnAuth, pid3.childIndex);
  //delete PIDsegment[pid3.childIndex];
}
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