如何在JavaScript中触发事件？

Question

我已将事件附加到文本框中addEventListener.它工作正常.当我想以编程方式从另一个函数触发事件时,我的问题出现了.

我该怎么做？

Answer 1

你可以在IE 8或更低版本上使用fireEvent,在大多数其他浏览器上使用w3c的dispatchEvent.要创建要触发的事件,您可以使用createEvent或createEventObject依赖浏览器.

下面是代码(从原型)一个不言自明一块触发一个事件dataavailable上的element:

var event; // The custom event that will be created
if(document.createEvent){
    event = document.createEvent("HTMLEvents");
    event.initEvent("dataavailable", true, true);
    event.eventName = "dataavailable";
    element.dispatchEvent(event);
} else {
    event = document.createEventObject();
    event.eventName = "dataavailable";
    event.eventType = "dataavailable";
    element.fireEvent("on" + event.eventType, event);
}

Answer 2

一个工作的例子:

// Add an event listener
document.addEventListener("name-of-event", function(e) {
  console.log(e.detail); // Prints "Example of an event"
});

// Create the event
var event = new CustomEvent("name-of-event", { "detail": "Example of an event" });

// Dispatch/Trigger/Fire the event
document.dispatchEvent(event);

对于旧版浏览器polyfill和更复杂的示例,请参阅MDN文档.

请参阅支持表格EventTarget.dispatchEvent和CustomEvent.

Answer 3

如果您不想使用JQuery并且不特别关注向后兼容性,请使用

let element = document.getElementById(id);
element.dispatchEvent(new Event("change")); // or whatever the event type might be

请参阅此处和此处的文档.

Answer 4

如果你使用jQuery,你可以简单地做

$('#yourElement').trigger('customEventName', [arg0, arg1, ..., argN]);

并处理它

$('#yourElement').on('customEventName',
   function (objectEvent, [arg0, arg1, ..., argN]){
       alert ("customEventName");
});

其中"[arg0,arg1,...,argN]"表示这些参数是可选的.

Answer 5

如果您支持IE9 +,则可以使用以下内容.同样的概念被包含在You Might Not Need jQuery中.

function addEventListener(el, eventName, handler) {
  if (el.addEventListener) {
    el.addEventListener(eventName, handler);
  } else {
    el.attachEvent('on' + eventName, function() {
      handler.call(el);
    });
  }
}

function triggerEvent(el, eventName, options) {
  var event;
  if (window.CustomEvent) {
    event = new CustomEvent(eventName, options);
  } else {
    event = document.createEvent('CustomEvent');
    event.initCustomEvent(eventName, true, true, options);
  }
  el.dispatchEvent(event);
}

// Add an event listener.
addEventListener(document, 'customChangeEvent', function(e) {
  document.body.innerHTML = e.detail;
});

// Trigger the event.
triggerEvent(document, 'customChangeEvent', {
  detail: 'Display on trigger...'
});

如果您已经在使用jQuery,那么这里是上面代码的jQuery版本.

$(function() {
  // Add an event listener.
  $(document).on('customChangeEvent', function(e, opts) {
    $('body').html(opts.detail);
  });

  // Trigger the event.
  $(document).trigger('customChangeEvent', {
    detail: 'Display on trigger...'
  });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

Answer 6

我使用JavaScript在mouseover上搜索了click click,mousedown和mouseup事件.我找到了Juan Mendes提供的答案.如需答案,请点击此处.

点击这里是现场演示,下面是代码:

function fireEvent(node, eventName) {
    // Make sure we use the ownerDocument from the provided node to avoid cross-window problems
    var doc;
    if (node.ownerDocument) {
        doc = node.ownerDocument;
    } else if (node.nodeType == 9) {
        // the node may be the document itself, nodeType 9 = DOCUMENT_NODE
        doc = node;
    } else {
        throw new Error("Invalid node passed to fireEvent: " + node.id);
    }

    if (node.dispatchEvent) {
        // Gecko-style approach (now the standard) takes more work
        var eventClass = "";

        // Different events have different event classes.
        // If this switch statement can't map an eventName to an eventClass,
        // the event firing is going to fail.
        switch (eventName) {
        case "click": // Dispatching of 'click' appears to not work correctly in Safari. Use 'mousedown' or 'mouseup' instead.
        case "mousedown":
        case "mouseup":
            eventClass = "MouseEvents";
            break;

        case "focus":
        case "change":
        case "blur":
        case "select":
            eventClass = "HTMLEvents";
            break;

        default:
            throw "fireEvent: Couldn't find an event class for event '" + eventName + "'.";
            break;
        }
        var event = doc.createEvent(eventClass);

        var bubbles = eventName == "change" ? false : true;
        event.initEvent(eventName, bubbles, true); // All events created as bubbling and cancelable.

        event.synthetic = true; // allow detection of synthetic events
        // The second parameter says go ahead with the default action
        node.dispatchEvent(event, true);
    } else if (node.fireEvent) {
        // IE-old school style
        var event = doc.createEventObject();
        event.synthetic = true; // allow detection of synthetic events
        node.fireEvent("on" + eventName, event);
    }
};

Answer 7

只是建议一个不需要手动调用监听器事件的替代方案:

无论您的事件监听器做什么,都将其移动到一个函数中并从事件监听器调用该函数.

然后,您还可以在其他任何地方调用该函数,以完成事件触发时所执行的操作.

我觉得这不那么"代码密集",更容易阅读.

Answer 8

接受的答案对我不起作用，createEvent 的都没有。

最后对我有用的是：

targetElement.dispatchEvent(
    new MouseEvent('click', {
        bubbles: true,
        cancelable: true,
        view: window,
}));

这是一个片段：

targetElement.dispatchEvent(
    new MouseEvent('click', {
        bubbles: true,
        cancelable: true,
        view: window,
}));

const clickBtn = document.querySelector('.clickme');
const viaBtn = document.querySelector('.viame');

viaBtn.addEventListener('click', function(event) {
    clickBtn.dispatchEvent(
        new MouseEvent('click', {
            bubbles: true,
            cancelable: true,
            view: window,
    }));
});

clickBtn.addEventListener('click', function(event) {
    console.warn(`I was accessed via the other button! A ${event.type} occurred!`);
});

从阅读：https : //developer.mozilla.org/en-US/docs/Web/API/MouseEvent

Answer 9

我只是使用了以下(似乎更简单):

element.blur();
element.focus();

在这种情况下,只有当值被真正改变时才会触发事件,正如您通过用户执行的正常焦点轨迹触发它一样.

Answer 10

修改了@ Dorian对IE工作的回答:

document.addEventListener("my_event", function(e) {
  console.log(e.detail);
});

var detail = 'Event fired';

try {

    // For modern browsers except IE:
    var event = new CustomEvent('my_event', {detail:detail});

} catch(err) {

  // If IE 11 (or 10 or 9...?) do it this way:

    // Create the event.
    var event = document.createEvent('Event');
    // Define that the event name is 'build'.
    event.initEvent('my_event', true, true);
    event.detail = detail;

}

// Dispatch/Trigger/Fire the event
document.dispatchEvent(event);

FIDDLE: https ://jsfiddle.net/z6zom9d0/1/

还请参见:https :
//caniuse.com/#feat=customevent