我已经使用addEventListener将事件附加到文本框。它工作得很好。当我想从另一个函数以编程方式触发事件时,问题就出现了。

我该怎么做呢?


当前回答

你可以使用下面的代码来使用Element方法触发事件:

if (!Element.prototype.triggerEvent) {
    Element.prototype.triggerEvent = function (eventName) {
        var event;

        if (document.createEvent) {
            event = document.createEvent("HTMLEvents");
            event.initEvent(eventName, true, true);
        } else {
            event = document.createEventObject();
            event.eventType = eventName;
        }

        event.eventName = eventName;

        if (document.createEvent) {
            this.dispatchEvent(event);
        } else {
            this.fireEvent("on" + event.eventType, event);
        }
    };
}

if (!Element.prototype.triggerEvent) { Element.prototype.triggerEvent = function (eventName) { var event; if (document.createEvent) { event = document.createEvent("HTMLEvents"); event.initEvent(eventName, true, true); } else { event = document.createEventObject(); event.eventType = eventName; } event.eventName = eventName; if (document.createEvent) { this.dispatchEvent(event); } else { this.fireEvent("on" + event.eventType, event); } }; } var input = document.getElementById("my_input"); var button = document.getElementById("my_button"); input.addEventListener('change', function (e) { alert('change event fired'); }); button.addEventListener('click', function (e) { input.value = "Bye World"; input.triggerEvent("change"); }); <input id="my_input" type="input" value="Hellow World"> <button id="my_button">Change Input</button>

其他回答

HTML

<a href="demoLink" id="myLink"> myLink </a>
<button onclick="fireLink(event)"> Call My Link </button>

JS

// click event listener of the link element --------------  
document.getElementById('myLink').addEventListener("click", callLink);
function callLink(e) {
    // code to fire
}

// function invoked by the button element ----------------
function fireLink(event) {                   
    document.getElementById('myLink').click();      // script calls the "click" event of the link element 
}

我使用JavaScript搜索了鼠标悬停时的触发点击,鼠标下拉和鼠标上拉事件。我找到了胡安·门德斯提供的答案。点击这里获取答案。

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);
    }
};

修改@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);

小提琴:https://jsfiddle.net/z6zom9d0/1/

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

注意:initEvent方法现在已弃用。其他回答功能最新的和建议的做法。


你可以在ie8或更低版本上使用fireEvent,在大多数其他浏览器上使用W3C的dispatchEvent。要创建想要触发的事件,可以根据浏览器使用createEvent或createEventObject。

下面是一段不言自明的代码(来自原型),它可以触发元素上可用的事件数据:

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);
}

值得注意的是,我们可以创建任何类型的预定义事件,并在任何地方收听。

我们并不局限于经典的内置事件。

在这个基本示例中,自定义事件interfacebuiltsuccessuserdefinedevent每3秒在self.document上分派一次

self.document。addEventListener('interfacebuiltsuccessuserdefinedevent', () => console.log("WOW"), false) setInterval(() =>{//测试 self.document。dispatchEvent(新事件(interfacebuiltsuccessuserdefinedevent)) }, 3000) //测试

有趣的事实:元素可以侦听尚未创建的事件。