CODEWITHSUNDEEP
javascriptarraysecmascript-6
Reacting
Reacting

Reputation: 6123

How can I check that a specific key in an array is empty at every index?

So I have an array of objects to iterate over, on every iteration I need to check if a key named blocks has or has no length.

If all of the blocks keys are empty (length === 0) then I need to do an operation, otherwise do not. Get it? If ONNLY ONE blocks key has a length > 0 then the operation should be avoided.

    for (let i = 0; i < blockColumns.length; i++) {
      if (!blockColumns[i].blocks.length) {
        // TRIGGER OPERATION
      }
    }

In the code above the problem is that the operation will be trigger when at least one blocks key has no length, which what I don't need. The operation should be trigger ONLY when all of the blocks keys have length === 0.

Upvotes: 0

Views: 82

Answers (4)

cabiste
cabiste

Reputation: 507

well then you can do

x = 0
for (let i = 0; i < blockColumns.length; i++) {
      if (!blockColumns[i].blocks.length > 0) {
        x+=1;
      }
    }
   if(x == blockColumns.length){
     //do something
    }

this is a very simple way of doing it and i don't think that it's efficient at all but it gets the job done for now :D

Upvotes: 1

Brooke Hart
Brooke Hart

Reputation: 4049

This sounds like something that Array.prototype.every would be useful for:

if (blockColumns.every((el) => el?.blocks?.length === 0)) {
    // Do your operation
}

I've used optional chaining here since I'm not sure if there might be a case where an element doesn't have a blocks property, or if that property may not have a length property. But depending on how confident you can be in your data structure, you may not need to do that.

Upvotes: 1

Ori Drori
Ori Drori

Reputation: 191976

Use Array.every() to check that every item has a 0 length (!0 === true). If all items have 0 length, the every would return true. If a false is encountered (ie length > 0), every would return false immediately.

const allEmpty = blockColumns.every(o => !o.blocks.length)

if(allEmpty) doSomething()

Upvotes: 2

Noah Brinton
Noah Brinton

Reputation: 109

   let doOperation = true;
   for (let i = 0; i < blockColumns.length; i++) {
       if (blockColumns[i].blocks.length > 0) {
           doOperation = false
       }
   }
   if (doOperation) {
       //Some operation
   }

not sure if I follow but would this work?

Upvotes: 0

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