onclick() and onblur() ordering issue

Question

I have an input field that brings up a custom drop-down menu. I would like the following functionality:

• When the user clicks anywhere outside the input field, the menu should be removed.
• If, more specifically, the user clicks on a div inside the menu, the menu should be removed, and special processing should occur based on which div was clicked.

Here is my implementation:

The input field has an onblur() event which deletes the menu (by setting its parent's innerHTML to an empty string) whenever the user clicks outside the input field. The divs inside the menu also have onclick() events which execute the special processing.

The problem is that the onclick() events never fire when the menu is clicked, because the input field's onblur() fires first and deletes the menu, including the onclick()s!

I solved the problem by splitting the menu divs' onclick() into onmousedown() and onmouseup() events and setting a global flag on mouse down which is cleared on mouse up, similar to what was suggested in this answer. Because onmousedown() fires before onblur(), the flag will be set in onblur() if one of the menu divs was clicked, but not if somewhere else on the screen was. If the menu was clicked, I immediately return from onblur() without deleting the menu, then wait for the onclick() to fire, at which point I can safely delete the menu.

Is there a more elegant solution?

The code looks something like this:

<div class="menu" onmousedown="setFlag()" onmouseup="doProcessing()">...</div>
<input id="input" onblur="removeMenu()" ... />

var mouseflag;

function setFlag() {
    mouseflag = true;
}

function removeMenu() {
    if (!mouseflag) {
        document.getElementById('menu').innerHTML = '';
    }
}

function doProcessing(id, name) {
    mouseflag = false;
    ...
}

Answer 1

I was having the exact same issue as you, my UI is designed exactly as you describe. I solved the problem by simply replacing the onClick for the menu items with an onMouseDown. I did nothing else; no onMouseUp, no flags. This resolved the problem by letting the browser automatically re-order based on the priority of these event handlers, without any additional work from me.

Is there any reason why this wouldn't have also worked for you?

Answer 2

onClick should not be replaced with onMouseDown.

While this approach somewhat works, the two are fundamentally different events that have different expectations in the eyes of the user. Using onMouseDown instead of onClick will ruin the predictability of your software in this case. Thus, the two events are noninterchangeable.

To illustrate: when accidentally clicking on a button, users expect to be able to hold down the mouse click, drag the cursor outside of the element, and release the mouse button, ultimately resulting in no action. onClick does this. onMouseDown doesn't allow the user to hold the mouse down, and instead will immediately trigger an action, without any recourse for the user. onClick is the standard by which we expect to trigger actions on a computer.

In this situation, call event.preventDefault() on the onMouseDown event. onMouseDown will cause a blur event by default, and will not do so when preventDefault is called. Then, onClick will have a chance to be called. A blur event will still happen, only after onClick.

After all, the onClick event is a combination of onMouseDown and onMouseUp, if and only if they both occur within the same element.

An example here

Answer 3

Replace on onmousedown with onfocus. So this event will be triggered when the focus is inside the textbox.

Replace on onmouseup with onblur. The moment you take out your focus out of textbox, onblur will execute.

I guess this is what you might need.

UPDATE:

when you execute your function onfocus-->remove the classes that you will apply in onblur and add the classes that you want to be executed onfocus

and

when you execute your function onblur-->remove the classes that you will apply in onfocus and add the classes that you want to be executed onblur

I don't see any need of flag variables.

UPDATE 2:

You can use the events onmouseout and onmouseover

onmouseover-Detects when the cursor is over it.

onmouseout-Detects when the cursor leaves.

Answer 4

onFocus / onBlur are events that don't bubble. There are however focus events that do bubble. These being focusin and focusout.

Now to the solution: We wrap both the input and our dropdown into a div-element and set the tabindex of that div to -1 (so that it can recieve focus / but does not appear in the tab order). We now add an eventlistener for focusin and focusout to this div. And since these events do bubble a click on our input element will trigger our divs focusin event (which opens the drop-down)

The neat part now is that a click on our dropdown will also trigger the focusin event on our div (so we basically maintain focus which means: focusout/blur never fires and our dropdown stays open)

You can try this out with the code snippit below (the dropdown only closes on loss of focus - but if you want it to close when clicking on the dropdown aswell just uncomment the one line of JS)

const container = document.getElementById("container")
const dropDown = document.getElementById("drop-down")

container.addEventListener("focusin", (event) => {
  dropDown.classList.toggle("hidden", false)
})
container.addEventListener("focusout", (event) => {
  dropDown.classList.toggle("hidden", true)
})
dropDown.addEventListener("click", (event) => {
  console.log("I - the drop down - have been clicked");
  //dropDown.classList.toggle("hidden", true);
});

.container {
  width: fit-content;
}

.drop-down {
  width: 100%;
  height: 200px;
  border: solid 1px black
}

.hidden {
  display: none
}

<div class="container" id="container" tabindex="-1">
  <input id="input" />
  <div class="drop-down hidden" id="drop-down" > Hi I'm a drop down </div>
</div>

there arises however one issue if you want to add your dropdown into the tabbing order, have buttons in your dropdown or in general have an element in the dropdown, that can recieve focus. Because then a click will give the element in the dropdown focus first. This triggers our container div to lose focus which closes the dropdown so the focus event can't bubble further and therefore can't trigger the focusin on our container.

We can solve this issue by expanding the focusout eventlistener a bit.

The new eventlistener is as follows:

container.addEventListener("focusout", (event) => {
  dropDown.classList.toggle("hidden", !container.matches(":hover"))
})

We basically say: "don't you close that dropDown if someone is hovering over it" (This solution only considers mouse-use; but in that case this is fine, because the problem this tries to fix only ever occured when using a mouse, when tabbing onto/through the dropDown everything worked fine from the start)

Answer 5

change onclick by onfocus

even if the onblur and onclick do not get along very well, but obviously onfocus and yes onblur. since even after the menu is closed the onfocus is still valid for the element clicked inside.

I did and it worked.

Answer 6

An ideal solution I found to work for me was to simply add a timeout in my onBlur function. I used 250ms, that provided smooth behaviour for my blur event and allowed my onClick to fire before the onBlur. I used this example as a reference https://erikmartinjordan.com/onblur-prevents-onclick-react

Answer 7

You can use a setInterval function inside your onBlur handler, like this:

<input id="input" onblur="removeMenu()" ... />

function removeMenu() {
    setInterval(function(){
        if (!mouseflag) {
            document.getElementById('menu').innerHTML = '';
        }
    }, 0);
}

the setInterval function will remove your onBlur function out from the call stack, add because you set time to 0, this function will be called immediately after other event handler finished