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Safely navigate a null scroll component (offsetHeight of null) #172

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merged 3 commits into from
Sep 14, 2018
Merged

Safely navigate a null scroll component (offsetHeight of null) #172

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ee0a262
Add a failing test case to simulate the error we are seeing in produc…
skovy Aug 14, 2018
927f775
Make changes to safely navigate null scrollComponent
skovy Aug 14, 2018
ac51e07
Rebuild the dist
skovy Aug 14, 2018
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25 changes: 20 additions & 5 deletions dist/InfiniteScroll.js
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Original file line number Diff line number Diff line change
Expand Up @@ -166,7 +166,7 @@ var InfiniteScroll = (function(_Component) {
{
key: 'getParentElement',
value: function getParentElement(el) {
return el.parentNode;
return el && el.parentNode;
},
},
{
Expand Down Expand Up @@ -241,9 +241,7 @@ var InfiniteScroll = (function(_Component) {
if (this.props.isReverse) {
offset = scrollTop;
} else {
offset =
this.calculateTopPosition(el) +
(el.offsetHeight - scrollTop - window.innerHeight);
offset = this.calculateOffset(el, scrollTop);
}
} else if (this.props.isReverse) {
offset = parentNode.scrollTop;
Expand All @@ -253,7 +251,11 @@ var InfiniteScroll = (function(_Component) {
}

// Here we make sure the element is visible as well as checking the offset
if (offset < Number(this.props.threshold) && el.offsetParent !== null) {
if (
offset < Number(this.props.threshold) &&
el &&
el.offsetParent !== null
) {
this.detachScrollListener();
// Call loadMore after detachScrollListener to allow for non-async loadMore functions
if (typeof this.props.loadMore === 'function') {
Expand All @@ -262,6 +264,19 @@ var InfiniteScroll = (function(_Component) {
}
},
},
{
key: 'calculateOffset',
value: function calculateOffset(el, scrollTop) {
if (!el) {
return 0;
}

return (
this.calculateTopPosition(el) +
(el.offsetHeight - scrollTop - window.innerHeight)
);
},
},
{
key: 'calculateTopPosition',
value: function calculateTopPosition(el) {
Expand Down
22 changes: 17 additions & 5 deletions src/InfiniteScroll.js
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Original file line number Diff line number Diff line change
Expand Up @@ -87,7 +87,7 @@ export default class InfiniteScroll extends Component {
}

getParentElement(el) {
return el.parentNode;
return el && el.parentNode;
}

filterProps(props) {
Expand Down Expand Up @@ -149,9 +149,7 @@ export default class InfiniteScroll extends Component {
if (this.props.isReverse) {
offset = scrollTop;
} else {
offset =
this.calculateTopPosition(el) +
(el.offsetHeight - scrollTop - window.innerHeight);
offset = this.calculateOffset(el, scrollTop);
}
} else if (this.props.isReverse) {
offset = parentNode.scrollTop;
Expand All @@ -160,7 +158,10 @@ export default class InfiniteScroll extends Component {
}

// Here we make sure the element is visible as well as checking the offset
if (offset < Number(this.props.threshold) && el.offsetParent !== null) {
if (
offset < Number(this.props.threshold) &&
(el && el.offsetParent !== null)
) {
this.detachScrollListener();
// Call loadMore after detachScrollListener to allow for non-async loadMore functions
if (typeof this.props.loadMore === 'function') {
Expand All @@ -169,6 +170,17 @@ export default class InfiniteScroll extends Component {
}
}

calculateOffset(el, scrollTop) {
if (!el) {
return 0;
}

return (
this.calculateTopPosition(el) +
(el.offsetHeight - scrollTop - window.innerHeight)
);
}

calculateTopPosition(el) {
if (!el) {
return 0;
Expand Down
24 changes: 24 additions & 0 deletions test/infiniteScroll_test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -75,4 +75,28 @@ describe('InfiniteScroll component', () => {
InfiniteScroll.prototype.attachScrollListener.restore();
InfiniteScroll.prototype.scrollListener.restore();
});

it('should handle when the scrollElement is removed from the DOM', () => {
const loadMore = stub();

const wrapper = mount(
<div>
<InfiniteScroll pageStart={0} loadMore={loadMore} hasMore={false}>
<div className="child-component">Child Text</div>
</InfiniteScroll>
</div>,
);

const component = wrapper.find(InfiniteScroll);

// The component has now mounted, but the scrollComponent is null
component.instance().scrollComponent = null;

// Invoke the scroll listener which depends on the scrollComponent to
// verify it executes properly, and safely navigates when the
// scrollComponent is null.
component.instance().scrollListener();

expect(wrapper.text()).to.contain('Child Text');
});
});