Can JavaScript Programmatically Open an HTML Select Dropdown Menu?

Can a JavaScript Program Automatically Open a Drop-Down Menu in an HTML Select Element?

Previously, it was possible to programmatically trigger the drop-down of an HTML select element using a combination of JavaScript and mouse event simulation. However, this method became deprecated and no longer works.

Why It No Longer Works

The W3C Working Draft for HTML5 states that interactive elements, including , should respond to non-click activations by running click activation steps on the element. This implies that programmatic click simulation should work.

Historical Proof of Concept

Trotz found that creating a MouseEvent object and dispatching it to a

element did indeed cause it to drop down. This was demonstrated in a working Fiddle.

showDropdown = function(element) {
  var event;
  event = document.createEvent('MouseEvents');
  event.initMouseEvent('mousedown', true, true, window);
  element.dispatchEvent(event);
};

Current Limitations

Unfortunately, this method is only supported in Chrome and no longer works in modern browsers. As such, it is not recommended to rely on it for production code.

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