Selecting nth-child of potentially infinite list of children

Question

I have a grid layout - 4 columns per row. I am using CSS grid layout.

Say there could potentially be an infinite number of items.

How could I select the two middle items of each row if the number of items is potentially infinite. For example for the first three rows I would need to select:

nth-child(2), nth-child(3), nth-child(6), nth-child(7), nth-child(10), nth-child(11)

I could hard code the styles up to a specific number assuming there wouldn't be an infinite number, but if there's a way to do it dynamically I'd rather do that.

user_6053654 · Answer

You can use .item:nth-child(4n+2) to target every fourth child (start from 2'nd child) and .item:nth-child(4n+3) to target every fourth child (start from 3'rd child). Here is the example:

.item:nth-child(4n+2),
.item:nth-child(4n+3) {
  color: red;
  background-color: yellow;
}

user_2802040 · Answer

Using the nth-child(xN+y) syntax...

.container {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-gap: 25px;
}

.box {
  padding: 1em;
  border: 1px solid grey;
}

.container :nth-child(4n+2) {
  background: red;
}

.container :nth-child(4n+3) {
  background: blue;
}

user_3313922 · Answer

Following is a js solution:

var items = document.getElementsByClassName('item');
for (i = 0; i < items.length; i++) {
  if(i % 2 === 0 && i % 4 === 0) {
    var el1 = items[i + 1];
    var el2 = items[i + 2];
    if (el1)
      el1.style.backgroundColor = "red";
    if (el2)
      el2.style.backgroundColor = "red";
  }
}

.grid {
  display:grid;
  grid-template-columns: 100px 100px 100px 100px;
}

.item {
  border:1px solid black;
  padding:20px;
  margin:4px;
}

Selecting nth-child of potentially infinite list of children

3 Answers