事件解绑与解绑的兼容代码

 //绑定事件的兼容
    function addEventListener(element, type, fn) {
        if (element.addEventListener) {
            element.addEventListener(type, fn, false)
        } else if (element.attachEvent) {
            element.attachEvent("on" + type, fn);
        } else {
            element["on" + type] = fn;
        }
    }
    
 //解绑事件的兼容
    function removeEventListener(element, type, fnName) {
        if (element.removeEventListener) {
            element.removeEventListener(type, fnName, false);
        } else if (element.detachEvent) {
            element.detachEvent('on' + type, fnName);
        } else {
            element["on" + type] = null
        }
    }
    
 //测试
    function f1() {
        console.log("first");
    }

    function f2() {
        console.log('second');
    }

    addEventListener(my$('btn1'), 'click', f1);
    addEventListener(my$('btn1'), 'click', f2);
    my$('btn2').onclick = function () {
        removeEventListener(my$('btn1'), 'click', f1)
    }