trigger-point

@stellar-apps/trigger-point

A component for triggering events when an element enters or exits the viewport. This component requires a top-level ViewportProvider.

Installation

yarn add @stellar-apps/trigger-point

Usage

import TriggerPoint from '@stellar-apps/trigger-point'


<TriggerPoint partial>
  {({triggerPointRef, isTriggered, status, direction, element}) => (
    <span ref={triggerPointRef}>
      {isTriggered ? 'in view' : 'not in view'}
      {" "}
      {status ? status : 'not yet triggered'}
    </span>
  )}
</TriggerPoint>

TriggerPoint

Props

• root {DOM Element}
  • default document
  • A specific ancestor of the target element being observed. If no value was passed to the constructor or this is null, the top-level document's viewport is used
• rootMargin {string}
  • default 0 0 0 0
  • Margin around the root. Can have values similar to the CSS margin property, e.g. "10px 20px 30px 40px" (top, right, bottom, left). The values can be percentages. This set of values serves to grow or shrink each side of the root element's bounding box before computing intersections.
• thresholds {number|Array}
  • default 0
  • Either a single number or an array of numbers which indicate at what percentage of the target's visibility the observer's callback should be executed. If you only want to detect when visibility passes the 50% mark, you can use a value of 0.5. If you want the callback to run every time visibility passes another 25%, you would specify the array [0, 0.25, 0.5, 0.75, 1]. The default is 0 (meaning as soon as even one pixel is visible, the callback will be run). A value of 1.0 means that the threshold isn't considered passed until every pixel is visible.
• pollInterval {number}
  • default null
  • The frequency in which the polyfill polls for intersection changes
  • Only relevant if you'd like to detect changes for any of the following:
    • CSS changes on :hover, :active, or :focus states
    • CSS changes due to transitions or animations with a long initial delay
    • Resizable <textarea> elements that cause other elements to move around
    • Scrolling of non-document elements in browsers that don't support the event capture phase
• disableMutationObserver {bool}
  • default false
  • You can choose to not check for intersections when the DOM changes by setting this property to true
• onEnter {func}
  • Callback event for when the element enters into the viewport
• onExit {func}
  • Callback event for when the element exits the viewport
• onEnterTop {func}
  • Callback event for when the element enters into the viewport from the top
• onExitTop {func}
  • Callback event for when the element exits the viewport from the top
• onEnterBottom {func}
  • Callback event for when the element enters into the viewport from the bottom
• onExitBottom {func}
  • Callback event for when the element exits the viewport from the bottom

Render props

• triggerPointRef {React.createRef}
  • A ref to provided to the element attached to the trigger point
• isTriggered {bool}
  • default false
  • Returns true if the element is currently in the viewport, false if not
• visibilityRatio {number}
  • default 0
  • Returns the ratio of the intersectionRect to the boundingClientRect. That is to say, it's the amount of the element that is current visible within the root.
• status {string}
  • default untriggered
  • One of untriggered, enterTop, exitTop, enterBottom, exitBottom. This represents the most recent status of the trigger event.
• direction {number}
  • default 0
  • The direction scrolling is happening. -1 for up, 1 for down, 0 for neutral
• scrollTop {number}
  • default 0
  • The y scroll position from the top of the @root where the latest intersection threshold was recorded.