How can I trigger a JavaScript event click

Question

I have a hyperlink in my page. I am trying to automate a number of clicks on the hyperlink for testing purposes. Is there any way you can simulate 50 clicks on the hyperlink using JavaScript?

<a href="#" target="_blank" onclick="javascript:Test("Test");">MSDN</a>

I'm looking for onClick event trigger from the JavaScript.

Answer 1

.click() does not work with Android (look at mozilla docs, at mobile section). You can trigger the click event with this method:

function fireClick(node){
    if (document.createEvent) {
        var evt = document.createEvent('MouseEvents');
        evt.initEvent('click', true, false);
        node.dispatchEvent(evt);    
    } else if (document.createEventObject) {
        node.fireEvent('onclick') ; 
    } else if (typeof node.onclick == 'function') {
        node.onclick(); 
    }
}

From this post

Answer 2

I'm quite ashamed that there are so many incorrect or undisclosed partial applicability.

The easiest way to do this is through Chrome or Opera (my examples will use Chrome) using the Console. Enter the following code into the console (generally in 1 line):

var l = document.getElementById('testLink');
for(var i=0; i<5; i++){
  l.click();
}

This will generate the required result

Answer 3

IE9+

function triggerEvent(el, type){
    var e = document.createEvent('HTMLEvents');
    e.initEvent(type, false, true);
    el.dispatchEvent(e);
}

Usage example:

var el = document.querySelector('input[type="text"]');
triggerEvent(el, 'mousedown');

Source: https://plainjs.com/javascript/events/trigger-an-event-11/

Answer 4

What

 l.onclick();

does is exactly calling the onclick function of l, that is, if you have set one with l.onclick = myFunction;. If you haven't set l.onclick, it does nothing. In contrast,

 l.click();

simulates a click and fires all event handlers, whether added with l.addEventHandler('click', myFunction);, in HTML, or in any other way.

Answer 5

Use a testing framework

This might be helpful - http://seleniumhq.org/ - Selenium is a web application automated testing system.

You can create tests using the Firefox plugin Selenium IDE

Manual firing of events

To manually fire events the correct way you will need to use different methods for different browsers - either el.dispatchEvent or el.fireEvent where el will be your Anchor element. I believe both of these will require constructing an Event object to pass in.

The alternative, not entirely correct, quick-and-dirty way would be this:

var el = document.getElementById('anchorelementid');
el.onclick(); // Not entirely correct because your event handler will be called
              // without an Event object parameter.

Answer 6

Here is what I use: http://jsfiddle.net/mendesjuan/rHMCy/4/

Updated to work with IE9+

/**
 * Fire an event handler to the specified node. Event handlers can detect that the event was fired programatically
 * by testing for a 'synthetic=true' property on the event object
 * @param {HTMLNode} node The node to fire the event handler on.
 * @param {String} eventName The name of the event without the "on" (e.g., "focus")
 */
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);
        event.initEvent(eventName, true, 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, you can drop this if you don't need to support IE8 and lower
        var event = doc.createEventObject();
        event.synthetic = true; // allow detection of synthetic events
        node.fireEvent("on" + eventName, event);
    }
};

Note that calling fireEvent(inputField, 'change'); does not mean it will actually change the input field. The typical use case for firing a change event is when you set a field programmatically and you want event handlers to be called since calling input.value="Something" won't trigger a change event.