The IntersectionObserver interface's read-only thresholds property returns the list of intersection thresholds that was specified when the observer was instantiated with IntersectionObserver(). If only one threshold ratio was provided when instantiating the object, this will be an array containing that single value.
See the Intersection Observer page to learn how thresholds work.
An array of intersection thresholds, originally specified using the threshold property when instantiating the observer. If only one observer was specified, without being in an array, this value is a one-entry array containing that threshold. Regardless of the order your original threshold array was in, this one is always sorted in numerically increasing order.
If no threshold option was included when IntersectionObserver() was used to instantiate the observer, the value of thresholds is [0].
Note: Although the options object you can specify when creating an IntersectionObserver has a field named threshold, this property is called thresholds. Confusing? Yes. If you accidentally use thresholds as the name of the field in your options, the thresholds array will wind up being [0.0], which is likely not what you expect. Debugging chaos may ensue.
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
thresholds |
52 | 15 | 55 | No | 39 | 12.1 | 52 | 52 | 55 | 41 | 12.2 | 6.0 |
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https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/thresholds