EleResize

一个允许监听元素resize事件的解决方案
此腳本不應該直接安裝，它是一個供其他腳本使用的函式庫。欲使用本函式庫，請在腳本 metadata 寫上： // @require https://update.gf.qytechs.cn/scripts/450831/1090316/EleResize.js
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換行
/**
 * Created by taozh on 2017/5/6.
 * [email protected]
 */
var EleResize = {
    _handleResize: function (e) {
        var ele = e.target || e.srcElement;
        var trigger = ele.__resizeTrigger__;
        if (trigger) {
            var handlers = trigger.__z_resizeListeners;
            if (handlers) {
                var size = handlers.length;
                for (var i = 0; i < size; i++) {
                    var h = handlers[i];
                    var handler = h.handler;
                    var context = h.context;
                    handler.apply(context, [e]);
                }
            }
        }
    },
    _removeHandler: function (ele, handler, context) {
        var handlers = ele.__z_resizeListeners;
        if (handlers) {
            var size = handlers.length;
            for (var i = 0; i < size; i++) {
                var h = handlers[i];
                if (h.handler === handler && h.context === context) {
                    handlers.splice(i, 1);
                    return;
                }
            }
        }
    },
    _createResizeTrigger: function (ele) {
        var obj = document.createElement('object');
        obj.setAttribute('style',
            'display: block; position: absolute; top: 0; left: 0; height: 100%; width: 100%; overflow: hidden;opacity: 0; pointer-events: none; z-index: -1;');
        obj.onload = EleResize._handleObjectLoad;
        obj.type = 'text/html';
        ele.appendChild(obj);
        obj.data = 'about:blank';
        return obj;
    },
    _handleObjectLoad: function (evt) {
        this.contentDocument.defaultView.__resizeTrigger__ = this.__resizeElement__;
        this.contentDocument.defaultView.addEventListener('resize', EleResize._handleResize);
    }
};
if (document.attachEvent) {//ie9-10
    EleResize.on = function (ele, handler, context) {
        var handlers = ele.__z_resizeListeners;
        if (!handlers) {
            handlers = [];
            ele.__z_resizeListeners = handlers;
            ele.__resizeTrigger__ = ele;
            ele.attachEvent('onresize', EleResize._handleResize);
        }
        handlers.push({
            handler: handler,
            context: context
        });
    };
    EleResize.off = function (ele, handler, context) {
        var handlers = ele.__z_resizeListeners;
        if (handlers) {
            EleResize._removeHandler(ele, handler, context);
            if (handlers.length === 0) {
                ele.detachEvent('onresize', EleResize._handleResize);
                delete ele.__z_resizeListeners;
            }
        }
    }
} else {
    EleResize.on = function (ele, handler, context) {
        var handlers = ele.__z_resizeListeners;
        if (!handlers) {
            handlers = [];
            ele.__z_resizeListeners = handlers;

            if (getComputedStyle(ele, null).position === 'static') {
                ele.style.position = 'relative';
            }
            var obj = EleResize._createResizeTrigger(ele);
            ele.__resizeTrigger__ = obj;
            obj.__resizeElement__ = ele;
        }
        handlers.push({
            handler: handler,
            context: context
        });
    };
    EleResize.off = function (ele, handler, context) {
        var handlers = ele.__z_resizeListeners;
        if (handlers) {
            EleResize._removeHandler(ele, handler, context);
            if (handlers.length === 0) {
                var trigger = ele.__resizeTrigger__;
                if (trigger) {
                    trigger.contentDocument.defaultView.removeEventListener('resize', EleResize._handleResize);
                    ele.removeChild(trigger);
                    delete ele.__resizeTrigger__;
                }
                delete ele.__z_resizeListeners;
            }
        }
    }
}