MediaQueryList.addListener()

The addListener() method of the MediaQueryList interface adds a listener to the MediaQueryListener that will run a custom callback function in response to the media query status changing.

This is basically an alias for EventTarget.addEventListener(), for backwards compatibility purposes. Older browsers should use addListener instead of addEventListener since MediaQueryList only inherits from EventTarget in newer browsers.

Syntax

MediaQueryList.addListener(func)

Parameters

func

A function or function reference representing the callback function you want to run when the media query status changes. In the original implementation, the callback was a non-standard MediaQueryListListener object. In the new implementation the standard event mechanism is used, the callback is a standard function, and the event object is a MediaQueryListEvent, which inherits from Event.

Return value

Void.

Examples

var para = document.querySelector('p');
var mql = window.matchMedia('(max-width: 600px)');

function screenTest(e) {
  if (e.matches) {
    /* the viewport is 600 pixels wide or less */
    para.textContent = 'This is a narrow screen — less than 600px wide.';
    document.body.style.backgroundColor = 'red';
  } else {
    /* the viewport is more than than 600 pixels wide */
    para.textContent = 'This is a wide screen — more than 600px wide.';
    document.body.style.backgroundColor = 'blue';
  }
}

mql.addListener(screenTest);

Specifications

Browser compatibility

See also

• Media queries
• Using media queries from code
• window.matchMedia()
• MediaQueryList
• MediaQueryListEvent