How to do such a check against a JS array?

• 0
  Good afternoon there is such an array.
  

  var arrayPositions = [493.19998931884766, 916.5999755859375, 1340, 1763.3999633789062, 2186.7999877929688, 2916.2001342773438, 3339.6000366210938, 4068.9999389648438, 4492.400085449219, 4915.799987792969]

  
  
  10 coordinates.
  These are the coordinates of the elements that I get through the each loop.
  Jquery has a function like this
  

  $(window).on('scroll', function () {
        var scroll = $(window).scrollTop();
    });

  
  
  Question
  How can I make such a check that if var scroll has values ​​greater than 0 of the element but less than 1, I get the index of 0 of the element. If, for example, the number is more than 4 elements but less than 5, I get its index
  
  And how correct is it to do such a check in Window.Scroll. function. After all, the check will be every time for every px

  JavaScript Jace Todd, Jul 21, 2019

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2 Answers
• 0
  We hope that the array is sorted.
  
  

  if (scroll < arrayPositions[0]) return;
  
  let index = arrayPositions.findIndex((el, i, arr) => scroll < arr[i + 1]);

  Anonymous

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• 0
  Just go through the array and find the position you want.
  
  
  
  

  $(window).on('scroll', function () {
  
        var scroll = $(window).scrollTop();
  
        let id_ = 0;
  
        for (const z in arrayPositions){
  
            if (z < scroll) {
  
                  id_++;
  
            }
  
       }
  
    });

  
  
  The id_ will store the position in the array.

  August Hickman

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