I am creating a popover, where I need to position it correctly based on the button's position that triggered it.

It starts like this:

<div id="popoverWrapper" class="popover-wrapper" style={popoverStyle}>
    <section id="popover" class="slds-popover slds-popover_walkthrough slds-popover_large slds-nubbin_left" role="dialog">
        <!--all the insides of the popover-->

I initially just tried a getter on popoverStyle, but when trying to do this.template.querySelector('.popover-wrapper'); it returned null. I thought maybe this was because the getter was happening before actual render.

So I moved the querySelector to the renderedCallback() hook. Putting in a break point, the html is definitely rendered by the time I get to this.template.querySelector('.popover-wrapper'); but it still doesn't find anything.

How might I be able to grab the element in my LWC so I can get its position and dimensions to be able to position properly where I want by finding a space that it will fit?

PS: popoverStyle is getting set to a string that looks like: position: absolute; z-index: 10001; top: ' + correctPositioning.offsetTop + 'px; left: ' + correctPositioning.offsetLeft + 'px;. I am not entirely sure this will even work, but I can't even find the popover element in my JS to try it out.

  • 1
    i tried your code in renderedCallback and it worked. Playgound link Commented Mar 15, 2019 at 14:58
  • Well, that makes it difficult lol. My component is on a Visualforce page, so I have a lightning component that creates an LWC table with buttons, and those buttons create the LWC popover that is having the issues. I wouldn't think it being nested like that would impact it, especially since I am doing this.template. But yeah, querySelector returned an empty object in my renderedCallback... Commented Mar 15, 2019 at 15:08
  • Are you sure there's no other errors loading your component? What does this.template.querySelectorAll("*") return in your components renderedCallback? Commented Jun 3, 2019 at 20:28
  • Can you try something similar - developer.salesforce.com/docs/component-library/tools/… Commented Feb 3, 2020 at 0:38

1 Answer 1


You probably have an error in your component related with the way that you are trying to set the styles, if you remove style={popoverStyle} the this.template.querySelector('.popover-wrapper') must return you the element and there you can set directly using JS, like:

let popup = this.template.querySelector('.popover-wrapper');
popup.style.position = 'absolute'; 
  • Hello @Pirata21, I tried your answer, it doesn't seem to work. I am trying to get the width value of an element in javascript. let mapWidth = this.template.querySelector('.map-root'); console.log(mapWidth.style.width);
    – sumchans
    Commented Apr 10, 2020 at 16:21

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