resize

文档视图调整大小时会触发 resize 事件。

基本信息

规范

DOM L3, CSSOM View

接口

UIEvent

是否冒泡

否

是否可取消默认

否

事件目标

defaultView (window)

默认行为

None

属性

案例

由于resize事件可以以较高的速率触发, 因此事件处理程序不应该执行计算开销很大的操作 (如 DOM 修改)。相反, 建议使用requestAnimationFrame, setTimeout or customEvent, 比如:

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
    ...
  }
}());