How can I trigger a JavaScript event click

UPDATE

This was an old answer. Nowadays you should just use click. For more advanced event firing, use dispatchEvent.

const body = document.body;

body.addEventListener('click', e => {
  console.log('clicked body');
});

console.log('Using click()');
body.click();

console.log('Using dispatchEvent');
body.dispatchEvent(new Event('click'));

Original Answer

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.

Performing a single click on an HTML element: Simply do element.click(). Most major browsers support this.

To repeat the click more than once: Add an ID to the element to uniquely select it:

<a href="#" target="_blank" id="my-link" onclick="javascript:Test('Test');">Google Chrome</a>

and call the .click() method in your JavaScript code via a for loop:

var link = document.getElementById('my-link');
for(var i = 0; i < 50; i++)
   link.click();