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<body data-controller="tooltip">
  <div id="tooltip" style="display: none;" data-target="tooltip.tooltip" class="tooltip">
      Tooltip with some medium info
  <span class="indented" data-action="mouseover->tooltip#show mouseout->tooltip#hide" data-tooltip-msg="This should show below instead" data-tooltip-above="-20">
    Close to the top
  <div class="blank-space">
    <div class="indented">
      <span class="block margin" data-action="mouseover->tooltip#show mouseout->tooltip#hide" data-tooltip-msg="Short and slightly more above" data-tooltip-above="50">
        A long sentence that we want to show something above
    <div class="indented">
      <span data-action="mouseover->tooltip#show mouseout->tooltip#hide" class="block margin" data-tooltip-msg="This message is still perfectly centered">
        A short sentence

  <span class="margin" data-action="mouseover->tooltip#show mouseout->tooltip#hide" data-tooltip-msg="This message isn't clipped and not centered">I'm close to the left</span>
  <div class="blank-space"></div>
  <div class="indented">
    <span data-action="mouseover->tooltip#show mouseout->tooltip#hide"
          data-tooltip-msg="This should show up just above">
      At the bottom of the page


                .blank-space {
  height: 200px;
  width: 100%;

.indented {
  margin-left: 100px;
  position: relative;

.block {
  display: inline-block;

.margin {
  margin: 20px 0;

.tooltip {
  border: 1px dotted #AAA;
  position: absolute;
  padding: 5px;
  border-radius: 3px;


                const application = Stimulus.Application.start();

class TooltipController extends Stimulus.Controller {
  // The tooltip controller assumes that the tooltip element isn't
  // contained by any element or parent element that has "position: relative"
  // If that is the case the positioning of the tooltip WILL break.

  // create an element <div data-target="tooltip.tooltip"></div>
  // this element will be filled with text.

  // for any element that should have a tooltip do the following
  // <span
  //  data-tooltip-msg="My tooltip message"
  //  data-action="mouseover->tooltip#show mouseout->tooltip#hide"
  //  data-tooltip-above="30"
  // ></span>

  // data-tooltip-msg -> The message that the tooltip should display
  // data-tooltip-width -> Width of tooltip
  // data-tooltip-above -> How many pixels above the parent element the tooltip should be
  //                       by default this is 30px.
  static targets = [ "tooltip" ]
  show(event) {
    const dataset =
    let above = Number( ? : 30)
    let tooltip = this.tooltipTarget
    tooltip.innerHTML =
    // re-paint before getting coordinates from tooltip
    let width = dataset.tooltipWidth ? `width: ${dataset.tooltipWidth}px` : '' = `display: block; ${width};`
    const ttLoc = tooltip.getBoundingClientRect()
    // getBoundingClientRect is viewport coordinates we need
    // height if we've scrolled. 
    const scroll = document.documentElement.scrollTop
    let targetPos =
    let yLoc = targetPos.y + scroll - above
    let xLoc = targetPos.x + targetPos.width / 2 - ttLoc.width / 2
    xLoc = xLoc < 0 ? 0 : xLoc = `position: absolute; top: ${yLoc}px; left: ${xLoc}px;`
  hide(event) {
    let tooltip = this.tooltipTarget = 'display: none;'

application.register("tooltip", TooltipController);