Using the Grid Shepherd Technique to Order Data with CSS

Shepherds are good at caring for their flocks, bringing order and structure to them. Even with hundreds of sheep, the shepherds would still drive them back to the farm at the end of the day.

When processing data, programmers often don't know whether the data is correctly filtered or sorted. It is especially painful when iterating over the array and then displaying data on the page, because it is not known where each element is received. Grid Shepherd is a technology that uses CSS Grid instead of JavaScript to help you locate and sort projects to where you want.

This is what we will explore in this article. Grid Shepherd technology can bring order and structure to the data we process, while giving us a clearer understanding of where and how data is used than ever before.

Let's get a deeper understanding.

Sort using JavaScript

We will start by iterating over an unordered array of farm animals. Imagine cows and sheep happily grazing in the fields. They can be combined programmatically using the Array.prototype.sort method and listed on the page:

 let animals = [
  { name: 'Edna', animal: 'cow' },
  { name: 'Liam', animal: 'sheep' },
  { name: 'Fink', animal: 'sheep' },
  { name: 'Olga', animal: 'cow' },
];
let sortedAnimals = animals.sort((a, b) => {
  if (a.animal > b.animal) return 1;
  return 0;
});
console.log(sortedAnimals);
/* return:
  [ { name: 'Elga', animal: 'cow' },
    { name: 'Olga', animal: 'cow' },
    { name: 'Liam', animal: 'sheep' },
    { name: 'Fink', animal: 'sheep' } ]
*/

Learn about Grid Shepherd

The Grid Shepherd method enables the sorting of data without using JavaScript . Instead, we rely on CSS Grid to do the job for us.

The structure is exactly the same as the JavaScript object array above, but is represented by a DOM node.

<main><div> Edna</div>
  <div>Liam</div>
  <div>Jenn</div>
  <div>Fink</div>
</main>

To manage these animals we have to surround them in a common area, which is what we use<main></main> The reason for the element. By setting display: grid , we create a grid formatting context where we can define the columns (or rows) that each animal should occupy.

 .sheep { grid-column: 1; }
.cow { grid-column: 2; }

Using grid-auto-flow: dense , each animal is automatically arranged to the first available location in each defined area. This can also be used with any number of different sorting options - just define another column and the data will magically be sorted into it.

 main {
  display: grid;
  grid-auto-flow: density;
}

.sheep { grid-column: 1; }
.cow { grid-column: 2; }

Advanced Sheep

We can further improve our management examples using CSS counters. This way, we can calculate the number of animals in each column and—apply the quantity query proposed by Heydon Pickering in Lea Verou’s 2011 speech—style conditionally based on the quantity.

Quantity queries depend on some sort of selector for counting classes - this is great for :nth-child(An B [of S]?) pseudo-class notation, but it is currently only available in Safari). This means we have to use the :nth-of-type() selector as a workaround.

We need some new element types to make it work. This can be done by Web Components or by renaming any HTML element to a custom name. This applies even if these elements are not in the HTML specification, because browsers use HTMLUnknownElement to represent undefined tags, which causes them to behave very similarly to div . The documentation now looks like this:

<fence><sheep> Lisa</sheep><sheep> Bonnie</sheep><cow> Olaf</cow><sheep> Jenn</sheep></fence>

Now we can access our custom element type. When the number of sheep or cows is equal to or less than 10, let's apply a red background.

 Sheep:nth-last-of-type(n 10),
sheep:nth-last-of-type(n 10) ~ sheep,
cow:nth-last-of-type(n 10),
cow:nth-last-of-type(n 10) ~ cow, {
  background-color: red;
}

Additionally, the counter can be simply implemented by using counter-reset: countsheep countcow; and using the before selector to locate each element and count upwards.

 sheep::before {
  counter-increment: countsheep;  
  content: counter(countsheep); 
}

Here we will use Vue to dynamically add and delete animals, using Vue transitions and two different sorting options. Watch how animals naturally occupy the correct columns, even if you add more animals and remove some:

Grid Shepherd can also be used for any unordered data:

• Separate and calculate voters in the poll (possibly as two parts, and their corresponding profile pictures) and insert them in real time;
• Group personnel/colleagues based on position, age, height; and
• Create any hierarchy

Management and accessibility

grid-auto-flow: dense does not change the DOM structure of the grid - it just visually reorders included elements. A side effect can be seen in the last example sorted alphabetically, as the counter numbers are mixed together. Changing the DOM structure will affect not only those who use screen readers, but also tab traversal.

Also note that a flat document structure may be detrimental to screen readers. Instead, I would treat these demo grids as graphics and provide longer textual alternative information.

ending!

It's very clever to see how powerful CSS layout tools like mesh can be used for use cases outside of traditional layout requirements and enter areas that might have required other languages ​​in the past. In this case, we can see how the layout advantages of CSS Grid and the dynamic data processing capabilities of JavaScript overlap, and how this gives us more choices – and the power – to bend the rendered data as we wish.

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