IntersectionObserver callback firing immediately on page load
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1
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I'm very new to the IntersectionObserver API, and I've been experimenting with this code:
let target = document.querySelector('.lazy-load');
let options = {
root: null,
rootMargin: '0px',
threshold: 0
}
let observer = new IntersectionObserver(callback, options);
observer.observe(target);
function callback() {
console.log('observer triggered.');
}
This seems to work as it should, and callback()
is called whenever .lazy-load
element enters the viewport, but callback()
also fires once when the page is initially loaded, which triggers `console.log('observer triggered.');
Is there a reason for this callback to be triggered when the page loads? Or is there a mistake in how I'm implementing this?
Edit: Altering the code to the below still fires the callback at page load.
let target = document.querySelector('.lazy-load');
let options = {
root: null,
rootMargin: '0px',
threshold: 0
}
let callback = function(entries, observer) {
entries.forEach(entry => {
console.log('observer triggered.');
});
};
let observer = new IntersectionObserver(callback, options);
observer.observe(target);
javascript lazy-loading intersection-observer
add a comment |
up vote
1
down vote
favorite
I'm very new to the IntersectionObserver API, and I've been experimenting with this code:
let target = document.querySelector('.lazy-load');
let options = {
root: null,
rootMargin: '0px',
threshold: 0
}
let observer = new IntersectionObserver(callback, options);
observer.observe(target);
function callback() {
console.log('observer triggered.');
}
This seems to work as it should, and callback()
is called whenever .lazy-load
element enters the viewport, but callback()
also fires once when the page is initially loaded, which triggers `console.log('observer triggered.');
Is there a reason for this callback to be triggered when the page loads? Or is there a mistake in how I'm implementing this?
Edit: Altering the code to the below still fires the callback at page load.
let target = document.querySelector('.lazy-load');
let options = {
root: null,
rootMargin: '0px',
threshold: 0
}
let callback = function(entries, observer) {
entries.forEach(entry => {
console.log('observer triggered.');
});
};
let observer = new IntersectionObserver(callback, options);
observer.observe(target);
javascript lazy-loading intersection-observer
add a comment |
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I'm very new to the IntersectionObserver API, and I've been experimenting with this code:
let target = document.querySelector('.lazy-load');
let options = {
root: null,
rootMargin: '0px',
threshold: 0
}
let observer = new IntersectionObserver(callback, options);
observer.observe(target);
function callback() {
console.log('observer triggered.');
}
This seems to work as it should, and callback()
is called whenever .lazy-load
element enters the viewport, but callback()
also fires once when the page is initially loaded, which triggers `console.log('observer triggered.');
Is there a reason for this callback to be triggered when the page loads? Or is there a mistake in how I'm implementing this?
Edit: Altering the code to the below still fires the callback at page load.
let target = document.querySelector('.lazy-load');
let options = {
root: null,
rootMargin: '0px',
threshold: 0
}
let callback = function(entries, observer) {
entries.forEach(entry => {
console.log('observer triggered.');
});
};
let observer = new IntersectionObserver(callback, options);
observer.observe(target);
javascript lazy-loading intersection-observer
I'm very new to the IntersectionObserver API, and I've been experimenting with this code:
let target = document.querySelector('.lazy-load');
let options = {
root: null,
rootMargin: '0px',
threshold: 0
}
let observer = new IntersectionObserver(callback, options);
observer.observe(target);
function callback() {
console.log('observer triggered.');
}
This seems to work as it should, and callback()
is called whenever .lazy-load
element enters the viewport, but callback()
also fires once when the page is initially loaded, which triggers `console.log('observer triggered.');
Is there a reason for this callback to be triggered when the page loads? Or is there a mistake in how I'm implementing this?
Edit: Altering the code to the below still fires the callback at page load.
let target = document.querySelector('.lazy-load');
let options = {
root: null,
rootMargin: '0px',
threshold: 0
}
let callback = function(entries, observer) {
entries.forEach(entry => {
console.log('observer triggered.');
});
};
let observer = new IntersectionObserver(callback, options);
observer.observe(target);
javascript lazy-loading intersection-observer
javascript lazy-loading intersection-observer
edited Nov 8 at 19:25
asked Nov 8 at 18:36
rpivovar
6741728
6741728
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
up vote
2
down vote
accepted
That is the default behaviour. When you instantiate an instance of the IntersectionObserver, the callback
will be fired.
It is recommended to guard against this case.
entries.forEach(entry => {
if (entry.intersectionRatio > 0) {
entry.target.classList.add('in-viewport');
} else {
entry.target.classList.remove('in-viewport');
}
});
Also I found this article as well as the docs to be very helpful, specifically about the intersectionRatio
or isIntersecting
properties on the IntersectionObserverEntry.
· https://www.smashingmagazine.com/2018/01/deferring-lazy-loading-intersection-observer-api/
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserverEntry
Awesome answer. Thanks.
– rpivovar
Nov 20 at 2:18
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
accepted
That is the default behaviour. When you instantiate an instance of the IntersectionObserver, the callback
will be fired.
It is recommended to guard against this case.
entries.forEach(entry => {
if (entry.intersectionRatio > 0) {
entry.target.classList.add('in-viewport');
} else {
entry.target.classList.remove('in-viewport');
}
});
Also I found this article as well as the docs to be very helpful, specifically about the intersectionRatio
or isIntersecting
properties on the IntersectionObserverEntry.
· https://www.smashingmagazine.com/2018/01/deferring-lazy-loading-intersection-observer-api/
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserverEntry
Awesome answer. Thanks.
– rpivovar
Nov 20 at 2:18
add a comment |
up vote
2
down vote
accepted
That is the default behaviour. When you instantiate an instance of the IntersectionObserver, the callback
will be fired.
It is recommended to guard against this case.
entries.forEach(entry => {
if (entry.intersectionRatio > 0) {
entry.target.classList.add('in-viewport');
} else {
entry.target.classList.remove('in-viewport');
}
});
Also I found this article as well as the docs to be very helpful, specifically about the intersectionRatio
or isIntersecting
properties on the IntersectionObserverEntry.
· https://www.smashingmagazine.com/2018/01/deferring-lazy-loading-intersection-observer-api/
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserverEntry
Awesome answer. Thanks.
– rpivovar
Nov 20 at 2:18
add a comment |
up vote
2
down vote
accepted
up vote
2
down vote
accepted
That is the default behaviour. When you instantiate an instance of the IntersectionObserver, the callback
will be fired.
It is recommended to guard against this case.
entries.forEach(entry => {
if (entry.intersectionRatio > 0) {
entry.target.classList.add('in-viewport');
} else {
entry.target.classList.remove('in-viewport');
}
});
Also I found this article as well as the docs to be very helpful, specifically about the intersectionRatio
or isIntersecting
properties on the IntersectionObserverEntry.
· https://www.smashingmagazine.com/2018/01/deferring-lazy-loading-intersection-observer-api/
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserverEntry
That is the default behaviour. When you instantiate an instance of the IntersectionObserver, the callback
will be fired.
It is recommended to guard against this case.
entries.forEach(entry => {
if (entry.intersectionRatio > 0) {
entry.target.classList.add('in-viewport');
} else {
entry.target.classList.remove('in-viewport');
}
});
Also I found this article as well as the docs to be very helpful, specifically about the intersectionRatio
or isIntersecting
properties on the IntersectionObserverEntry.
· https://www.smashingmagazine.com/2018/01/deferring-lazy-loading-intersection-observer-api/
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver
· https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserverEntry
answered Nov 20 at 2:14
snewcomer
130110
130110
Awesome answer. Thanks.
– rpivovar
Nov 20 at 2:18
add a comment |
Awesome answer. Thanks.
– rpivovar
Nov 20 at 2:18
Awesome answer. Thanks.
– rpivovar
Nov 20 at 2:18
Awesome answer. Thanks.
– rpivovar
Nov 20 at 2:18
add a comment |
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