resize

The resize event is fired when the document view has been resized.

General info

Specifications

DOM L3, CSSOM View

Interface

UIEvent

Bubbles

No

Cancelable

No

Target

defaultView (window)

Default Action

None

Properties

Property	Type	Description
target Read only	EventTarget	The event target (the topmost target in the DOM tree).
type Read only	DOMString	The type of event.
bubbles Read only	Boolean	Whether the event normally bubbles or not
cancelable Read only	Boolean	Whether the event is cancellable or not?
view Read only	WindowProxy	document.defaultView (window of the document)
detail Read only	long (float)	0.

Examples

Since resize events can fire at a high rate, the event handler shouldn't execute computationally expensive operations such as DOM modifications. Instead, it is recommended to throttle the event using requestAnimationFrame, setTimeout or customEvent, as follows:

requestAnimationFrame + customEvent

(function() {
    var throttle = function(type, name, obj) {
        obj = obj || window;
        var running = false;
        var func = function() {
            if (running) { return; }
            running = true;
             requestAnimationFrame(function() {
                obj.dispatchEvent(new CustomEvent(name));
                running = false;
            });
        };
        obj.addEventListener(type, func);
    };

    /* init - you can init any event */
    throttle("resize", "optimizedResize");
})();

// handle event
window.addEventListener("optimizedResize", function() {
    console.log("Resource conscious resize callback!");
});

requestAnimationFrame

var optimizedResize = (function() {

    var callbacks = [],
        running = false;

    // fired on resize event
    function resize() {

        if (!running) {
            running = true;

            if (window.requestAnimationFrame) {
                window.requestAnimationFrame(runCallbacks);
            } else {
                setTimeout(runCallbacks, 66);
            }
        }

    }

    // run the actual callbacks
    function runCallbacks() {

        callbacks.forEach(function(callback) {
            callback();
        });

        running = false;
    }

    // adds callback to loop
    function addCallback(callback) {

        if (callback) {
            callbacks.push(callback);
        }

    }

    return {
        // public method to add additional callback
        add: function(callback) {
            if (!callbacks.length) {
                window.addEventListener('resize', resize);
            }
            addCallback(callback);
        }
    }
}());

// start process
optimizedResize.add(function() {
    console.log('Resource conscious resize callback!')
});

setTimeout

(function() {

  window.addEventListener("resize", resizeThrottler, false);

  var resizeTimeout;
  function resizeThrottler() {
    // ignore resize events as long as an actualResizeHandler execution is in the queue
    if ( !resizeTimeout ) {
      resizeTimeout = setTimeout(function() {
        resizeTimeout = null;
        actualResizeHandler();
     
       // The actualResizeHandler will execute at a rate of 15fps
       }, 66);
    }
  }

  function actualResizeHandler() {
    // handle the resize event
    ...
  }

}());