modal-readability-outside | BrowserStack Docs

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Severity: Serious

Description

If screen readers read elements outside the modal when a modal is open, users can get confused about performing the required action on the modal.

This rule ensures that screen readers can’t read any content outside the modal when a modal is open.

To comply with this rule, you can assign aria-hidden=true to the elements outside the modal and aria-modal="true" to the element containing the modal when the modal is open. When the modal is closed, remove aria-hidden=true from the elements for screen readers to access them.

Examples

Consider the following example in which a modal is opened without setting aria-hidden=true to the elements outside the modal or setting aria-modal="true" to the element containing the modal.

Copy

Without dynamically handling aria-hidden or aria-modal attributes, screen readers can read elements outside the modal even when the modal is open. This breaks the modal-readability-outside rule.

In contrast, the following example dynamically sets aria-hidden=true to the elements outside the modal and aria-modal="true" to the element containing the modal when the modal is open. When the modal is closed, the aria-hidden attribute is hidden.

```javascript
// Get modal element
const modal = document.getElementById("myModal");

// Get main content to toggle aria-hidden
const mainContent = document.getElementById("mainContent");

// Get button that opens the modal
const btn = document.getElementById("openModalBtn");

// Get the <span> element that closes the modal
const closeBtn = document.getElementsByClassName("close")[0];

// Function to hide content from screen readers and show modal
function openModal() {
  modal.style.display = "block";
  mainContent.setAttribute("aria-hidden", "true");  // Hide main content
  modal.setAttribute("aria-modal", "true");  // Set aria-modal to true
}

// Function to show content to screen readers and hide modal
function closeModal() {
  modal.style.display = "none";
  mainContent.removeAttribute("aria-hidden");  // Show main content
  modal.removeAttribute("aria-modal");  // Remove aria-modal attribute
}

// When the user clicks the button, open the modal
btn.onclick = function() {
  openModal();
}

// When the user clicks on <span> (x), close the modal
closeBtn.onclick = function() {
  closeModal();
}

// When the user clicks anywhere outside of the modal, close it
window.onclick = function(event) {
  if (event.target === modal) {
    closeModal();
  }
}

// Helper function to set aria-hidden on all siblings except modal
function setAriaHiddenForSiblings(hidden) {
  const siblings = Array.from(document.body.children).filter((child) => 
    child !== modal && child.tagName !== 'SCRIPT' && child.tagName !== 'STYLE'
  );
  
  siblings.forEach(sibling => {
    if (hidden) {
      sibling.setAttribute('aria-hidden', 'true');
    } else {
      sibling.removeAttribute('aria-hidden');
    }
  });
}

// Override openModal and closeModal to handle aria-hidden on all siblings
function openModal() {
  modal.style.display = "block";
  setAriaHiddenForSiblings(true);  // Hide all sibling elements except modal
  modal.setAttribute("aria-modal", "true");  // Set aria-modal to true
}

function closeModal() {
  modal.style.display = "none";
  setAriaHiddenForSiblings(false);  // Remove aria-hidden from sibling elements
  modal.removeAttribute("aria-modal");  // Remove aria-modal attribute
}
```

Copy

Screen readers can’t read elements outside the modal in this scenario when the modal is open. Thus, this modified code does not violate the modal-readability-outside rule.

How to fix?

Follow these steps to fix the modal-readability-outside rule if it gets flagged:

Identify any modals used on your webpage.
Check if you have programmed aria-hidden=true to the elements outside the modal and aria-modal="true" to the element containing the modal when the modal is open.
If not, modify the JavaScript code to dynamically assign aria-hidden=true to the elements outside the modal and aria-modal="true" to the element containing the modal when the modal is open.
Modify the JavaScript code to dynamically remove aria-hidden=true from the elements when the modal is closed so that screen readers can access them.

Reference

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