reading-order

<integer>

Represents the ordinal group the element belongs to.

When an element's block, flex, or grid parent container has a reading-flow property set to a value other than normal, the reading-order property can be used to set the element's reading flow position relative to that of its siblings.

For reading and navigation, elements inside a block, flex, or grid container are sorted by ascending reading-order value. If multiple siblings have the same reading-order value, those items are sorted according to the container's reading-flow. Siblings not given an explicit reading-order value are assigned the default value of 0, which puts all the children of a reading flow container in the same ordinal group by default.

Sibling elements are ordered starting from the lowest numbered ordinal group to the highest. Therefore, to cause an element to be read out after its siblings, you could set a reading-order value or 1 or more on it. To cause an element to be read out before its siblings, you could set a reading-order value or -1 or less on it.

The reading-order defines the reading and tabbing order, but has no effect on visual order.

If a set of reading flow container child elements that are not normally focusable are made focusable with tabindex="0" attributes, their reading order will be modified as expected by the reading-flow and reading-order properties, in just the same way as interactive elements such as <a> or <button>.

However, any attempt to modify the tabbing order of a reading flow container's content using positive tabindex values will be ignored — overriden by the effects of reading-flow and reading-order. You generally shouldn't be using these anyway; see Don't Use Tabindex Greater than 0. The reading-flow and reading-order properties provide a much better way to modify tabbing order if required.

This example demonstrates using reading-order to control the positions of individual grid items within a grid container's reading order. One grid item has a reading-order value that is lower than the default 0, so will be read out before its sibling elements. Another has a higher reading-order value set, so will be read out after the others, regardless of source or display order.

HTML

In our markup we have six <a> elements contained inside a wrapper <div>.

<div class="wrapper">
  <a href="#">Item 1</a>
  <a class="bottom" href="#">Item 2</a>
  <a href="#">Item 3</a>
  <a class="top" href="#">Item 4</a>
  <a href="#">Item 5</a>
  <a href="#">Item 6</a>
</div>

CSS

On the <div>, we set the grid-auto-flow property to dense, therefore items may display out of source order. The reading-order property on the <a> element with a class of top is set to -1, therefore "Item 4" will be the first item in reading flow. The reading-order property on the <a> element with a class of bottom is set to 21, therefore "Item 4" will be the last item in the reading order. The remaining items will be visited in between, in grid row order, as the <div> element's reading-flow property is set to grid-rows.

.wrapper {
  display: grid;
  grid-template-columns: repeat(3, 150px);
  grid-auto-flow: dense;
  reading-flow: grid-rows;
}

.top {
  reading-order: -1;
}

.bottom {
  reading-order: 21;
}

Result

The above demo renders as follows:

Try tabbing through the links. Note how "Item 4" is tabbed to first and "Item 2" is tabbed to last because of their modified reading-order values. In between, the items are tabbed to in grid row order.

In this example, the odd-numbered items have a lower reading-order value set, so will be read out before the others in a group, regardless of source or display order.

HTML

In our markup, we have five <a> elements contained inside a wrapper <div>.

<div class="wrapper">
  <a href="#">Item 1</a>
  <a href="#">Item 2</a>
  <a href="#">Item 3</a>
  <a href="#">Item 4</a>
  <a href="#">Item 5</a>
</div>

CSS

The <div> element's reading-flow property is set to source-order, which allows reading-order to be used to override the default source reading order. The odd-numbered <a> elements have a reading-order value of -1, therefore they are read out before the even-numbered items.

.wrapper {
  reading-flow: source-order;
}

.wrapper > a {
  display: block;
}

.wrapper a:nth-child(odd) {
  reading-order: -1;
}

Result

The above demo renders as follows:

Try tabbing through the links, and note how "Item 1", "Item 3", and "Item 5" are tabbed to first because of their modified reading-order. After that, the items are tabbed to in source order.

• reading-flow
• CSS reading-flow examples via chrome.dev