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intersection-observer-test.js
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/**
* Copyright 2016 Google Inc. All Rights Reserved.
*
* Licensed under the W3C SOFTWARE AND DOCUMENT NOTICE AND LICENSE.
*
* https://www.w3.org/Consortium/Legal/2015/copyright-software-and-document
*
*/
// Sets the timeout to three times the poll interval to ensure all updates
// happen (especially in slower browsers). Native implementations get the
// standard 100ms timeout defined in the spec.
var ASYNC_TIMEOUT = IntersectionObserver.prototype.THROTTLE_TIMEOUT * 3 || 100;
var io;
var noop = function() {};
// References to DOM elements, which are accessible to any test
// and reset prior to each test so state isn't shared.
var rootEl;
var grandParentEl;
var parentEl;
var targetEl1;
var targetEl2;
var targetEl3;
var targetEl4;
describe('IntersectionObserver', function() {
before(function() {
// If the browser running the tests doesn't support MutationObserver,
// fall back to polling.
if (!('MutationObserver' in window)) {
IntersectionObserver.prototype.POLL_INTERVAL =
IntersectionObserver.prototype.THROTTLE_TIMEOUT || 100;
}
});
beforeEach(function() {
addStyles();
addFixtures();
});
afterEach(function() {
if (io && 'disconnect' in io) io.disconnect();
io = null;
removeStyles();
removeFixtures();
});
describe('constructor', function() {
it('throws when callback is not a function', function() {
expect(function() {
io = new IntersectionObserver(null);
}).to.throwException();
});
it('instantiates root correctly', function() {
io = new IntersectionObserver(noop);
expect(io.root).to.be(null);
io = new IntersectionObserver(noop, {root: rootEl});
expect(io.root).to.be(rootEl);
});
it('throws when root is not an Element', function() {
expect(function() {
io = new IntersectionObserver(noop, {root: 'foo'});
}).to.throwException();
});
it('instantiates rootMargin correctly', function() {
io = new IntersectionObserver(noop, {rootMargin: '10px'});
expect(io.rootMargin).to.be('10px 10px 10px 10px');
io = new IntersectionObserver(noop, {rootMargin: '10px -5%'});
expect(io.rootMargin).to.be('10px -5% 10px -5%');
io = new IntersectionObserver(noop, {rootMargin: '10px 20% 0px'});
expect(io.rootMargin).to.be('10px 20% 0px 20%');
io = new IntersectionObserver(noop, {rootMargin: '0px 0px -5% 5px'});
expect(io.rootMargin).to.be('0px 0px -5% 5px');
// TODO(philipwalton): the polyfill supports fractional pixel and
// percentage values, but the native Chrome implementation does not,
// at least not in what it reports `rootMargin` to be.
if (!supportsNativeIntersectionObserver()) {
io = new IntersectionObserver(noop, {rootMargin: '-2.5% -8.5px'});
expect(io.rootMargin).to.be('-2.5% -8.5px -2.5% -8.5px');
}
});
// TODO(philipwalton): this doesn't throw in FF, consider readding once
// expected behavior is clarified.
// it('throws when rootMargin is not in pixels or pecernt', function() {
// expect(function() {
// io = new IntersectionObserver(noop, {rootMargin: '0'});
// }).to.throwException();
// });
// Chrome's implementation in version 51 doesn't include the thresholds
// property, but versions 52+ do.
if ('thresholds' in IntersectionObserver.prototype) {
it('instantiates thresholds correctly', function() {
io = new IntersectionObserver(noop);
expect(io.thresholds).to.eql([0]);
io = new IntersectionObserver(noop, {threshold: 0.5});
expect(io.thresholds).to.eql([0.5]);
io = new IntersectionObserver(noop, {threshold: [0.25, 0.5, 0.75]});
expect(io.thresholds).to.eql([0.25, 0.5, 0.75]);
io = new IntersectionObserver(noop, {threshold: [1, .5, 0]});
expect(io.thresholds).to.eql([0, .5, 1]);
});
}
it('throws when a threshold is not a number', function() {
expect(function() {
io = new IntersectionObserver(noop, {threshold: ['foo']});
}).to.throwException();
});
it('throws when a threshold value is not between 0 and 1', function() {
expect(function() {
io = new IntersectionObserver(noop, {threshold: [0, -1]});
}).to.throwException();
});
});
describe('observe', function() {
it('throws when target is not an Element', function() {
expect(function() {
io = new IntersectionObserver(noop);
io.observe(null);
}).to.throwException();
});
it('triggers for all targets when observing begins', function(done) {
io = new IntersectionObserver(function(records) {
expect(records.length).to.be(2);
expect(records[0].intersectionRatio).to.be(1);
expect(records[1].intersectionRatio).to.be(0);
done();
}, {root: rootEl});
targetEl2.style.top = '-40px';
io.observe(targetEl1);
io.observe(targetEl2);
});
it('triggers for existing targets when observing begins after monitoring has begun', function(done) {
var spy = sinon.spy();
io = new IntersectionObserver(spy, {root: rootEl});
io.observe(targetEl1);
setTimeout(function() {
io.observe(targetEl2);
setTimeout(function() {
expect(spy.callCount).to.be(2);
done();
}, ASYNC_TIMEOUT);
}, ASYNC_TIMEOUT);
});
it('triggers with the correct arguments', function(done) {
io = new IntersectionObserver(function(records, observer) {
expect(records.length).to.be(2);
expect(records[0] instanceof IntersectionObserverEntry).to.be.ok();
expect(records[1] instanceof IntersectionObserverEntry).to.be.ok();
expect(observer).to.be(io);
expect(this).to.be(io);
done();
}, {root: rootEl});
targetEl2.style.top = '-40px';
io.observe(targetEl1);
io.observe(targetEl2);
});
it('handles container elements with non-visible overflow',
function(done) {
var spy = sinon.spy();
io = new IntersectionObserver(spy, {root: rootEl});
runSequence([
function(done) {
io.observe(targetEl1);
setTimeout(function() {
expect(spy.callCount).to.be(1);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(1);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.left = '-40px';
setTimeout(function() {
expect(spy.callCount).to.be(2);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(0);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
parentEl.style.overflow = 'visible';
setTimeout(function() {
expect(spy.callCount).to.be(3);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(1);
done();
}, ASYNC_TIMEOUT);
}
], done);
});
it('observes one target at a single threshold correctly', function(done) {
var spy = sinon.spy();
io = new IntersectionObserver(spy, {root: rootEl, threshold: 0.5});
runSequence([
function(done) {
targetEl1.style.left = '-5px';
io.observe(targetEl1);
setTimeout(function() {
expect(spy.callCount).to.be(1);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be.greaterThan(0.5);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.left = '-15px';
setTimeout(function() {
expect(spy.callCount).to.be(2);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be.lessThan(0.5);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.left = '-25px';
setTimeout(function() {
expect(spy.callCount).to.be(2);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.left = '-10px';
setTimeout(function() {
expect(spy.callCount).to.be(3);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(0.5);
done();
}, ASYNC_TIMEOUT);
}
], done);
});
it('observes multiple targets at multiple thresholds correctly',
function(done) {
var spy = sinon.spy();
io = new IntersectionObserver(spy, {
root: rootEl,
threshold: [1, 0.5, 0]
});
runSequence([
function(done) {
targetEl1.style.top = '0px';
targetEl1.style.left = '-15px';
targetEl2.style.top = '-5px';
targetEl2.style.left = '0px';
targetEl3.style.top = '0px';
targetEl3.style.left = '205px';
io.observe(targetEl1);
io.observe(targetEl2);
io.observe(targetEl3);
setTimeout(function() {
expect(spy.callCount).to.be(1);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(3);
expect(records[0].target).to.be(targetEl1);
expect(records[0].intersectionRatio).to.be(0.25);
expect(records[1].target).to.be(targetEl2);
expect(records[1].intersectionRatio).to.be(0.75);
expect(records[2].target).to.be(targetEl3);
expect(records[2].intersectionRatio).to.be(0);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.top = '0px';
targetEl1.style.left = '-5px';
targetEl2.style.top = '-15px';
targetEl2.style.left = '0px';
targetEl3.style.top = '0px';
targetEl3.style.left = '195px';
setTimeout(function() {
expect(spy.callCount).to.be(2);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(3);
expect(records[0].target).to.be(targetEl1);
expect(records[0].intersectionRatio).to.be(0.75);
expect(records[1].target).to.be(targetEl2);
expect(records[1].intersectionRatio).to.be(0.25);
expect(records[2].target).to.be(targetEl3);
expect(records[2].intersectionRatio).to.be(0.25);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.top = '0px';
targetEl1.style.left = '5px';
targetEl2.style.top = '-25px';
targetEl2.style.left = '0px';
targetEl3.style.top = '0px';
targetEl3.style.left = '185px';
setTimeout(function() {
expect(spy.callCount).to.be(3);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(3);
expect(records[0].target).to.be(targetEl1);
expect(records[0].intersectionRatio).to.be(1);
expect(records[1].target).to.be(targetEl2);
expect(records[1].intersectionRatio).to.be(0);
expect(records[2].target).to.be(targetEl3);
expect(records[2].intersectionRatio).to.be(0.75);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.top = '0px';
targetEl1.style.left = '15px';
targetEl2.style.top = '-35px';
targetEl2.style.left = '0px';
targetEl3.style.top = '0px';
targetEl3.style.left = '175px';
setTimeout(function() {
expect(spy.callCount).to.be(4);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].target).to.be(targetEl3);
expect(records[0].intersectionRatio).to.be(1);
done();
}, ASYNC_TIMEOUT);
}
], done);
});
it('handles rootMargin properly', function(done) {
parentEl.style.overflow = 'visible';
targetEl1.style.top = '0px';
targetEl1.style.left = '-20px';
targetEl2.style.top = '-20px';
targetEl2.style.left = '0px';
targetEl3.style.top = '0px';
targetEl3.style.left = '200px';
targetEl4.style.top = '180px';
targetEl4.style.left = '180px';
runSequence([
function(done) {
io = new IntersectionObserver(function(records) {
records = sortRecords(records);
expect(records.length).to.be(4);
expect(records[0].target).to.be(targetEl1);
expect(records[0].intersectionRatio).to.be(1);
expect(records[1].target).to.be(targetEl2);
expect(records[1].intersectionRatio).to.be(.5);
expect(records[2].target).to.be(targetEl3);
expect(records[2].intersectionRatio).to.be(.5);
expect(records[3].target).to.be(targetEl4);
expect(records[3].intersectionRatio).to.be(1);
io.disconnect();
done();
}, {root: rootEl, rootMargin: '10px'});
io.observe(targetEl1);
io.observe(targetEl2);
io.observe(targetEl3);
io.observe(targetEl4);
},
function(done) {
io = new IntersectionObserver(function(records) {
records = sortRecords(records);
expect(records.length).to.be(4);
expect(records[0].target).to.be(targetEl1);
expect(records[0].intersectionRatio).to.be(0.5);
expect(records[1].target).to.be(targetEl2);
expect(records[1].intersectionRatio).to.be(0);
expect(records[2].target).to.be(targetEl3);
expect(records[2].intersectionRatio).to.be(0.5);
expect(records[3].target).to.be(targetEl4);
expect(records[3].intersectionRatio).to.be(0.5);
io.disconnect();
done();
}, {root: rootEl, rootMargin: '-10px 10%'});
io.observe(targetEl1);
io.observe(targetEl2);
io.observe(targetEl3);
io.observe(targetEl4);
},
function(done) {
io = new IntersectionObserver(function(records) {
records = sortRecords(records);
expect(records.length).to.be(4);
expect(records[0].target).to.be(targetEl1);
expect(records[0].intersectionRatio).to.be(0.5);
expect(records[1].target).to.be(targetEl2);
expect(records[1].intersectionRatio).to.be(0);
expect(records[2].target).to.be(targetEl3);
expect(records[2].intersectionRatio).to.be(0);
expect(records[3].target).to.be(targetEl4);
expect(records[3].intersectionRatio).to.be(0.5);
io.disconnect();
done();
}, {root: rootEl, rootMargin: '-5% -2.5% 0px'});
io.observe(targetEl1);
io.observe(targetEl2);
io.observe(targetEl3);
io.observe(targetEl4);
},
function(done) {
io = new IntersectionObserver(function(records) {
records = sortRecords(records);
expect(records.length).to.be(4);
expect(records[0].target).to.be(targetEl1);
expect(records[0].intersectionRatio).to.be(0.5);
expect(records[1].target).to.be(targetEl2);
expect(records[1].intersectionRatio).to.be(0.5);
expect(records[2].target).to.be(targetEl3);
expect(records[2].intersectionRatio).to.be(0);
expect(records[3].target).to.be(targetEl4);
expect(records[3].intersectionRatio).to.be(0.25);
io.disconnect();
done();
}, {root: rootEl, rootMargin: '5% -2.5% -10px -190px'});
io.observe(targetEl1);
io.observe(targetEl2);
io.observe(targetEl3);
io.observe(targetEl4);
}
], done);
});
it('handles targets on the boundary of root', function(done) {
var spy = sinon.spy();
io = new IntersectionObserver(spy, {root: rootEl});
runSequence([
function(done) {
targetEl1.style.top = '0px';
targetEl1.style.left = '-21px';
targetEl2.style.top = '-20px';
targetEl2.style.left = '0px';
io.observe(targetEl1);
io.observe(targetEl2);
setTimeout(function() {
expect(spy.callCount).to.be(1);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(2);
expect(records[0].intersectionRatio).to.be(0);
expect(records[0].target).to.be(targetEl1);
expect(records[0].isIntersecting).to.be(false);
expect(records[1].intersectionRatio).to.be(0);
expect(records[1].target).to.be(targetEl2);
expect(records[1].isIntersecting).to.be(true);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.top = '0px';
targetEl1.style.left = '-20px';
targetEl2.style.top = '-21px';
targetEl2.style.left = '0px';
setTimeout(function() {
expect(spy.callCount).to.be(2);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(2);
expect(records[0].intersectionRatio).to.be(0);
expect(records[0].target).to.be(targetEl1);
expect(records[1].intersectionRatio).to.be(0);
expect(records[1].target).to.be(targetEl2);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.top = '-20px';
targetEl1.style.left = '200px';
targetEl2.style.top = '200px';
targetEl2.style.left = '200px';
setTimeout(function() {
expect(spy.callCount).to.be(3);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(0);
expect(records[0].target).to.be(targetEl2);
done();
}, ASYNC_TIMEOUT);
}
], done);
});
it('handles zero-size targets within the root coordinate space',
function(done) {
io = new IntersectionObserver(function(records) {
expect(records.length).to.be(1);
expect(records[0].isIntersecting).to.be(true);
expect(records[0].intersectionRatio).to.be(1);
done();
}, {root: rootEl});
targetEl1.style.top = '0px';
targetEl1.style.left = '0px';
targetEl1.style.width = '0px';
targetEl1.style.height = '0px';
io.observe(targetEl1);
});
it('handles elements with display set to none', function(done) {
var spy = sinon.spy();
io = new IntersectionObserver(spy, {root: rootEl});
runSequence([
function(done) {
rootEl.style.display = 'none';
io.observe(targetEl1);
setTimeout(function() {
expect(spy.callCount).to.be(1);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].isIntersecting).to.be(false);
expect(records[0].intersectionRatio).to.be(0);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
rootEl.style.display = 'block';
setTimeout(function() {
expect(spy.callCount).to.be(2);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].isIntersecting).to.be(true);
expect(records[0].intersectionRatio).to.be(1);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
parentEl.style.display = 'none';
setTimeout(function() {
expect(spy.callCount).to.be(3);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].isIntersecting).to.be(false);
expect(records[0].intersectionRatio).to.be(0);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
parentEl.style.display = 'block';
setTimeout(function() {
expect(spy.callCount).to.be(4);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].isIntersecting).to.be(true);
expect(records[0].intersectionRatio).to.be(1);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
targetEl1.style.display = 'none';
setTimeout(function() {
expect(spy.callCount).to.be(5);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].isIntersecting).to.be(false);
expect(records[0].intersectionRatio).to.be(0);
done();
}, ASYNC_TIMEOUT);
}
], done);
});
it('handles target elements not yet added to the DOM', function(done) {
var spy = sinon.spy();
io = new IntersectionObserver(spy, {root: rootEl});
// targetEl5 is initially not in the DOM. Note that this element must be
// created outside of the addFixtures() function to catch the IE11 error
// described here: https://github.com/w3c/IntersectionObserver/pull/205
var targetEl5 = document.createElement('div');
targetEl5.setAttribute('id', 'target5');
runSequence([
function(done) {
io.observe(targetEl5);
setTimeout(function() {
// Initial observe should trigger with no intersections since
// targetEl5 is not yet in the DOM.
expect(spy.callCount).to.be(1);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].isIntersecting).to.be(false);
expect(records[0].intersectionRatio).to.be(0);
expect(records[0].target).to.be(targetEl5);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
// Adding targetEl5 inside rootEl should trigger.
parentEl.insertBefore(targetEl5, targetEl2);
setTimeout(function() {
expect(spy.callCount).to.be(2);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(1);
expect(records[0].target).to.be(targetEl5);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
// Removing an ancestor of targetEl5 should trigger.
grandParentEl.parentNode.removeChild(grandParentEl);
setTimeout(function() {
expect(spy.callCount).to.be(3);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(0);
expect(records[0].target).to.be(targetEl5);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
// Adding the previously removed targetEl5 (via grandParentEl)
// back directly inside rootEl should trigger.
rootEl.appendChild(targetEl5);
setTimeout(function() {
expect(spy.callCount).to.be(4);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(1);
expect(records[0].target).to.be(targetEl5);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
// Removing rootEl should trigger.
rootEl.parentNode.removeChild(rootEl);
setTimeout(function() {
expect(spy.callCount).to.be(5);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(0);
expect(records[0].target).to.be(targetEl5);
done();
}, ASYNC_TIMEOUT);
}
], done);
});
if ('attachShadow' in Element.prototype) {
it('handles targets in shadow DOM', function(done) {
grandParentEl.attachShadow({mode: 'open'});
grandParentEl.shadowRoot.appendChild(parentEl);
io = new IntersectionObserver(function(records) {
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(1);
done();
}, {root: rootEl});
io.observe(targetEl1);
});
it('handles roots in shadow DOM', function(done) {
var shadowRoot = grandParentEl.attachShadow({mode: 'open'});
shadowRoot.innerHTML =
'<style>' +
'#slot-parent {' +
' position: relative;' +
' width: 400px;' +
' height: 200px;' +
'}' +
'</style>' +
'<div id="slot-parent"><slot></slot></div>';
var slotParent = shadowRoot.getElementById('slot-parent');
io = new IntersectionObserver(function(records) {
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(1);
done();
}, {root: slotParent});
io.observe(targetEl1);
});
}
it('handles sub-root element scrolling', function(done) {
io = new IntersectionObserver(function(records) {
expect(records.length).to.be(1);
expect(records[0].intersectionRatio).to.be(1);
done();
}, {root: rootEl});
io.observe(targetEl3);
setTimeout(function() {
parentEl.scrollLeft = 40;
}, 0);
});
// Only run this test in browsers that support CSS transitions.
if ('transform' in document.documentElement.style &&
'transition' in document.documentElement.style) {
it('supports CSS transitions and transforms', function(done) {
targetEl1.style.top = '220px';
targetEl1.style.left = '220px';
io = new IntersectionObserver(function(records) {
expect(records.length).to.be(1);
// Chrome's native implementation sometimes incorrectly reports
// the intersection ratio as a number > 1.
expect(records[0].intersectionRatio >= 1);
done();
}, {root: rootEl, threshold: [1]});
// CSS transitions that are slower than the default throttle timeout
// require polling to detect, which can be set on a per-instance basis.
if (!supportsNativeIntersectionObserver()) {
io.POLL_INTERVAL = 100;
}
io.observe(targetEl1);
setTimeout(function() {
targetEl1.style.transform = 'translateX(-40px) translateY(-40px)';
}, 0);
});
}
it('uses the viewport when no root is specified', function(done) {
io = new IntersectionObserver(function(records) {
var viewportWidth =
document.documentElement.clientWidth || document.body.clientWidth;
var viewportHeight =
document.documentElement.clientHeight || document.body.clientHeight;
expect(records.length).to.be(1);
expect(records[0].rootBounds.top).to.be(0);
expect(records[0].rootBounds.left).to.be(0);
expect(records[0].rootBounds.right).to.be(viewportWidth);
expect(records[0].rootBounds.width).to.be(viewportWidth);
expect(records[0].rootBounds.bottom).to.be(viewportHeight);
expect(records[0].rootBounds.height).to.be(viewportHeight);
done();
});
// Ensures targetEl1 is visible in the viewport before observing.
window.scrollTo(0, 0);
rootEl.style.position = 'absolute';
rootEl.style.top = '0px';
rootEl.style.left = '0px';
io.observe(targetEl1);
});
});
describe('takeRecords', function() {
it('supports getting records before the callback is invoked',
function(done) {
var lastestRecords = [];
io = new IntersectionObserver(function(records) {
lastestRecords = lastestRecords.concat(records);
}, {root: rootEl});
io.observe(targetEl1);
window.requestAnimationFrame && requestAnimationFrame(function() {
lastestRecords = lastestRecords.concat(io.takeRecords());
});
setTimeout(function() {
expect(lastestRecords.length).to.be(1);
expect(lastestRecords[0].intersectionRatio).to.be(1);
done();
}, ASYNC_TIMEOUT);
});
});
describe('unobserve', function() {
it('removes targets from the internal store', function(done) {
var spy = sinon.spy();
io = new IntersectionObserver(spy, {root: rootEl});
runSequence([
function(done) {
targetEl1.style.top = targetEl2.style.top = '0px';
targetEl1.style.left = targetEl2.style.left = '0px';
io.observe(targetEl1);
io.observe(targetEl2);
setTimeout(function() {
expect(spy.callCount).to.be(1);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(2);
expect(records[0].target).to.be(targetEl1);
expect(records[0].intersectionRatio).to.be(1);
expect(records[1].target).to.be(targetEl2);
expect(records[1].intersectionRatio).to.be(1);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
io.unobserve(targetEl1);
targetEl1.style.top = targetEl2.style.top = '0px';
targetEl1.style.left = targetEl2.style.left = '-40px';
setTimeout(function() {
expect(spy.callCount).to.be(2);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(1);
expect(records[0].target).to.be(targetEl2);
expect(records[0].intersectionRatio).to.be(0);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
io.unobserve(targetEl2);
targetEl1.style.top = targetEl2.style.top = '0px';
targetEl1.style.left = targetEl2.style.left = '0px';
setTimeout(function() {
expect(spy.callCount).to.be(2);
done();
}, ASYNC_TIMEOUT);
}
], done);
});
});
describe('disconnect', function() {
it('removes all targets and stops listening for changes', function(done) {
var spy = sinon.spy();
io = new IntersectionObserver(spy, {root: rootEl});
runSequence([
function(done) {
targetEl1.style.top = targetEl2.style.top = '0px';
targetEl1.style.left = targetEl2.style.left = '0px';
io.observe(targetEl1);
io.observe(targetEl2);
setTimeout(function() {
expect(spy.callCount).to.be(1);
var records = sortRecords(spy.lastCall.args[0]);
expect(records.length).to.be(2);
expect(records[0].target).to.be(targetEl1);
expect(records[0].intersectionRatio).to.be(1);
expect(records[1].target).to.be(targetEl2);
expect(records[1].intersectionRatio).to.be(1);
done();
}, ASYNC_TIMEOUT);
},
function(done) {
io.disconnect();
targetEl1.style.top = targetEl2.style.top = '0px';
targetEl1.style.left = targetEl2.style.left = '-40px';
setTimeout(function() {
expect(spy.callCount).to.be(1);
done();
}, ASYNC_TIMEOUT);
}
], done);
});
});
});
/**
* Runs a sequence of function and when finished invokes the done callback.
* Each function in the sequence is invoked with its own done function and
* it should call that function once it's complete.
* @param {Array<Function>} functions An array of async functions.
* @param {Function} done A final callback to be invoked once all function
* have run.
*/
function runSequence(functions, done) {
var next = functions.shift();
if (next) {
next(function() {
runSequence(functions, done);
});
} else {
done && done();
}
}
/**
* Returns whether or not the current browser has native support for
* IntersectionObserver.
* @return {boolean} True if native support is detected.
*/
function supportsNativeIntersectionObserver() {
return 'IntersectionObserver' in window &&
window.IntersectionObserver.toString().indexOf('[native code]') > -1;
}
/**
* Sorts an array of records alphebetically by ascending ID. Since the current
* native implementation doesn't sort change entries by `observe` order, we do
* that ourselves for the non-polyfill case. Since all tests call observe
* on targets in sequential order, this should always match.
* https://crbug.com/613679
* @param {Array<IntersectionObserverEntry>} entries The entries to sort.
* @return {Array<IntersectionObserverEntry>} The sorted array.
*/
function sortRecords(entries) {
if (supportsNativeIntersectionObserver()) {
entries = entries.sort(function(a, b) {
return a.target.id < b.target.id ? -1 : 1;
});
}
return entries;
}
/**
* Adds the common styles used by all tests to the page.
*/
function addStyles() {