resize

resize event 当文档视图被调整大小时触发。

General info

Specifications: DOM L3, CSSOM View
Interface: UIEvent
Bubbles: No
Cancelable: No
Target: defaultView (window)
Default Action: None

Properties

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

}());