Question

166

Check inside a loop that array has next element in Javascript/QML

rated 0 times [ 168] [ 2] / answers: 1 / hits: 16713 / 9 Years ago, sun, august 23, 2015, 12:00:00

I have an array items. I need to make sure that in the current iteration of the loop I can safely call the next item of the array

for(var i = 0; i < items.length; ++i) {



  // do some stuff with current index e.g....

  item = items[i];





   // then do something with item @ i+1

   if(items[i+1]) {

      //do stuff 

   }



}

Is this how it is done or if not how/what would be the better way?

P.S. I do not want to do a bound check

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kristopherw

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3 Years ago

answered 9 Years ago longd · Accepted Answer

If you want to loop through every element except the last one (which doesn't have an element after it), you should do as suggested:

for(var i = 0; i < items.length-1; ++i) {

    // items[i+1] will always exist inside this loop

}

If, however, you want to loop through every element -even the last one-, and just add a condition if there is an element after, just move that same condition inside your loop:

for(var i = 0; i < items.length; ++i) {

    // do stuff on every element

    if(i < items.length-1){

        // items[i+1] will always exist inside this condition

    }

}

if(items[i+1]) will return false (and not execute the condition) if the next element contains a falsey value like false, 0, (an empty String returns false).