情况有点像
var someVar = some_other_function();
someObj.addEventListener("click", function(){
some_function(someVar);
}, false);
问题是someVar的值在addEventListener的侦听器函数中是不可见的,在addEventListener中它可能被视为一个新变量。
情况有点像
var someVar = some_other_function();
someObj.addEventListener("click", function(){
some_function(someVar);
}, false);
问题是someVar的值在addEventListener的侦听器函数中是不可见的,在addEventListener中它可能被视为一个新变量。
当前回答
完美的解决方案是使用闭包,像这样:
function makeSizer(size) { return function () { document.body.style.fontSize = `${size}px`; }; } //pass parameters here and keep the reference in variables: const size12 = makeSizer(12); const size24 = makeSizer(24); const size36 = makeSizer(36); document.getElementById('size-12').addEventListener("click", size12); document.getElementById('size-24').addEventListener("click", size24); document.getElementById('size-36').addEventListener("click", size36); document.getElementById('remove-12').addEventListener("click", ()=>{ document.getElementById('size-12').removeEventListener("click", size12); alert("Now click on 'size 12' button and you will see that there is no event listener any more"); }); test<br/> <button id="size-12"> size 12 </button> <button id="size-24"> size 24 </button> <button id="size-36"> size 36 </button> <button id="remove-12"> remove 12 </button>
因此,基本上你将一个函数包装在另一个函数中,并将其分配给一个变量,你可以注册为事件侦听器,但也可以取消注册!
其他回答
其他替代方法,可能没有bind的使用那么优雅,但它对于循环中的事件是有效的
for (var key in catalog){
document.getElementById(key).my_id = key
document.getElementById(key).addEventListener('click', function(e) {
editorContent.loadCatalogEntry(e.srcElement.my_id)
}, false);
}
它已经测试了谷歌chrome扩展和可能e.srcElement必须替换为e.srcElement在其他浏览器
我发现这个解决方案使用Imatoria发布的评论,但我不能标记为有用的,因为我没有足够的声誉:D
一个简单的方法就是这样
window.addEventListener('click', (e) => functionHandler(e, ...args));
对我有用。
var EV = {
ev: '',
fn: '',
elem: '',
add: function () {
this.elem.addEventListener(this.ev, this.fn, false);
}
};
function cons() {
console.log('some what');
}
EV.ev = 'click';
EV.fn = cons;
EV.elem = document.getElementById('body');
EV.add();
//If you want to add one more listener for load event then simply add this two lines of code:
EV.ev = 'load';
EV.add();
如果以后想要删除事件侦听器,那么创建对curry函数的引用是一个不错的选择。
在下面的代码中,我将说明我的意思。
// This is the curry function. We return a new function with the signature of what the click-listener expects
const handleClick = (foo, bar) => (clickEvent) => {
console.log('we get our custom input', foo, bar);
console.log('we get the click event too', clickEvent);
}
// We need to store a reference to the listener, making sure we are removing the correct reference later
const myListener = handleClick('foo', 'bar'); // Remember that we now return the actual event-handler
const btn = document.getElementById('btn'); // find the element to attach the listener to
btn.addEventListener('click', myListener);
// remove the event listener like this by using our reference
btn.removeEventListener('click', myListener);
下面是CodePen上的一个工作示例
完美的解决方案是使用闭包,像这样:
function makeSizer(size) { return function () { document.body.style.fontSize = `${size}px`; }; } //pass parameters here and keep the reference in variables: const size12 = makeSizer(12); const size24 = makeSizer(24); const size36 = makeSizer(36); document.getElementById('size-12').addEventListener("click", size12); document.getElementById('size-24').addEventListener("click", size24); document.getElementById('size-36').addEventListener("click", size36); document.getElementById('remove-12').addEventListener("click", ()=>{ document.getElementById('size-12').removeEventListener("click", size12); alert("Now click on 'size 12' button and you will see that there is no event listener any more"); }); test<br/> <button id="size-12"> size 12 </button> <button id="size-24"> size 24 </button> <button id="size-36"> size 36 </button> <button id="remove-12"> remove 12 </button>
因此,基本上你将一个函数包装在另一个函数中,并将其分配给一个变量,你可以注册为事件侦听器,但也可以取消注册!