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Minimally support iframes (nested browsing contexts) in selection event handling #12037

Merged
merged 29 commits into from
Aug 2, 2018
Merged

Minimally support iframes (nested browsing contexts) in selection event handling #12037

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6940e33
Prefer node’s window and document over globals
acusti Jan 17, 2018
3f3c1d7
Support active elements in nested browsing contexts
acusti Jan 17, 2018
b08a270
Merge branch 'master' into minimal-iframes
acusti Jan 22, 2018
51be426
Avoid invoking defaultView getter unnecessarily
acusti Jan 23, 2018
3714067
Prefer node’s window and document over globals
acusti Jan 17, 2018
66b8766
Support active elements in nested browsing contexts
acusti Jan 17, 2018
75bc65e
Avoid invoking defaultView getter unnecessarily
acusti Jan 23, 2018
5a61b66
Implement selection event fixtures
Jan 29, 2018
f752792
Prefer node’s window and document over globals
acusti Jan 17, 2018
a8fcf05
Avoid invoking defaultView getter unnecessarily
acusti Jan 23, 2018
0003681
Fix react-scripts to work with alphas after 16.0.0
Feb 12, 2018
fef8519
Run prettier on new selection events fixtures
Feb 12, 2018
799ee39
Add fixture for onSelect in iframes, remove DraftJS fixture
Feb 13, 2018
6e3d4b7
Merge branch 'minimal-iframes' of github.com:brandcast/react into min…
acusti Mar 30, 2018
d1ad016
Purge remnants of draft.js from fixtures
acusti Apr 2, 2018
3c32963
Use prop-types import instead of window global
acusti Apr 2, 2018
3f7b5c5
Make fixtures’ Iframe component Firefox-compatible
acusti Apr 2, 2018
05d8969
Merge branch 'master' into minimal-iframes
acusti Apr 5, 2018
a776570
Merge branch 'master' into minimal-iframes
acusti May 17, 2018
26e9d82
Merge branch 'master' into minimal-iframes
wilsonhyng Jul 13, 2018
4db5c44
Fix switch case for SelectionEventsFixture
wilsonhyng Jul 16, 2018
ccf0329
Remove draft.js / immutable.js dependencies
wilsonhyng Jul 17, 2018
2edf1f8
Cache owner doc as var to avoid reading it twice
wilsonhyng Jul 17, 2018
db02b65
Add documentation for getActiveElementDeep to explain try/catch
wilsonhyng Jul 18, 2018
75b9992
Ensure getActiveElement always returns DOM element
wilsonhyng Jul 24, 2018
0f1de45
Tighten up isNode and isTextNode
wilsonhyng Jul 24, 2018
95b2aef
Remove ie8 compatibility
wilsonhyng Jul 24, 2018
d997ba8
Specify cross-origin example in getActiveElementDeep
wilsonhyng Aug 2, 2018
e63391c
Revert back to returning null if document is not defined
wilsonhyng Aug 2, 2018
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14 changes: 10 additions & 4 deletions packages/react-dom/src/client/ReactDOMSelection.js
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,11 @@ import {TEXT_NODE} from '../shared/HTMLNodeType';
* @return {?object}
*/
export function getOffsets(outerNode) {
const selection = window.getSelection && window.getSelection();
let win = window;
if (outerNode.ownerDocument && outerNode.ownerDocument.defaultView) {
win = outerNode.ownerDocument.defaultView;
}
const selection = win.getSelection && win.getSelection();

if (!selection || selection.rangeCount === 0) {
return null;
Expand Down Expand Up @@ -150,11 +154,13 @@ export function getModernOffsetsFromPoints(
* @param {object} offsets
*/
export function setOffsets(node, offsets) {
if (!window.getSelection) {
const doc = node.ownerDocument || document;

if (!doc.defaultView.getSelection) {
return;
}

const selection = window.getSelection();
const selection = doc.defaultView.getSelection();
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defaultView is defined as a getter, and since we don't expect it to change within setOffsets maybe we should store the value in a local variable so we avoid triggering the getter twice.

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I made that change (for this line and two other instances) in 51be426

const length = node[getTextContentAccessor()].length;
let start = Math.min(offsets.start, length);
let end = offsets.end === undefined ? start : Math.min(offsets.end, length);
Expand All @@ -180,7 +186,7 @@ export function setOffsets(node, offsets) {
) {
return;
}
const range = document.createRange();
const range = doc.createRange();
range.setStart(startMarker.node, startMarker.offset);
selection.removeAllRanges();

Expand Down
24 changes: 21 additions & 3 deletions packages/react-dom/src/client/ReactInputSelection.js
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,25 @@ import * as ReactDOMSelection from './ReactDOMSelection';
import {ELEMENT_NODE} from '../shared/HTMLNodeType';

function isInDocument(node) {
return containsNode(document.documentElement, node);
return (
node &&
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Why do we need to check if node exists? In what situation will node not be a DOM node?

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The value that gets passed in comes from fbjs/lib/getActiveElement, which returns a nullable HTMLElement (https://github.com/facebook/fbjs/blob/master/packages/fbjs/src/core/dom/getActiveElement.js#L21). The only instance where the return value would be null is if the util was unable to find a document object, which I think would only happen in SSR. But because it is theoretically nullable, all the operations in this file first confirm that node (or elem, in hasSelectionCapabilities) is truthy.

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We don't use fbjs/lib/getActiveElement anymore, and have copied it in the repo. Let's tighten this up? Feel free to change getActiveElement as you see fit.

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@gaearon We can update getActiveElement.js to look like:

export default function getActiveElement(doc: ?Document): Element {
  doc = doc || document;
  try {
    return doc.activeElement || doc.body;
  } catch (e) {
    return doc.body;
  }
}

But strictly speaking, flow will still complain that document.body can be null (ref: facebook/flow#4783 (comment)), so strictly speaking, the Element return value still has to be ?Element, unless we did something like

export default function getActiveElement(doc: ?Document): Element {
  doc = doc || document;
  const body = doc.body || doc.createElement('body');
  try {
    return doc.activeElement || body;
  } catch (e) {
    return body;
  }
}

Do you have a preferred approach?

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I want to lean towards the first, but I keep reasoning out of it in favor of the second. Body could be null, and it really it should never happen. But I've been surprised too much before :).

With the second example, do you need a try/catch?

Also: do you anticipate any problems with code downstream working with a document body that isn't attached?

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@nhunzaker No try/catch needed for the second example, and the ReactInputSelection plugin won’t have any issues; the code is already setup to handle detached DOM elements for a case where the active element becomes detached between when it is first read and cached and after React finishes committing an update. The second option has grown on me; I suggested it thinking it was silly, but now feel like it’s pretty reasonable. If we go with that one, should we add a comment explaining that document.body can be null?

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The second option has grown on me; I suggested it thinking it was silly, but now feel like it’s pretty reasonable. If we go with that one, should we add a comment explaining that document.body can be null?

Let's go with it 👍

node.ownerDocument &&
containsNode(node.ownerDocument.documentElement, node)
);
}

function getActiveElementDeep() {
let win = window;
let element = getActiveElement();
while (element instanceof win.HTMLIFrameElement) {
try {
win = element.contentDocument.defaultView;
} catch (e) {
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What exactly are we catching here? Is it defaultView access throwing? Or do we expect contentDocument to potentially be missing?

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If you just try to access the contentDocument of an HTMLIframeElement that comes from a non-matching (separate) domain (like if there’s an embedded YouTube player in the DOM), the browser will throw an error.

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Could you add a comment to this line describing such a scenario?

return element;
}
element = getActiveElement(win.document);
}
return element;
}

/**
Expand All @@ -33,7 +51,7 @@ export function hasSelectionCapabilities(elem) {
}

export function getSelectionInformation() {
const focusedElem = getActiveElement();
const focusedElem = getActiveElementDeep();
return {
focusedElem: focusedElem,
selectionRange: hasSelectionCapabilities(focusedElem)
Expand All @@ -48,7 +66,7 @@ export function getSelectionInformation() {
* nodes and place them back in, resulting in focus being lost.
*/
export function restoreSelection(priorSelectionInformation) {
const curFocusedElem = getActiveElement();
const curFocusedElem = getActiveElementDeep();
const priorFocusedElem = priorSelectionInformation.focusedElem;
const priorSelectionRange = priorSelectionInformation.selectionRange;
if (curFocusedElem !== priorFocusedElem && isInDocument(priorFocusedElem)) {
Expand Down
48 changes: 33 additions & 15 deletions packages/react-dom/src/events/SelectEventPlugin.js
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Original file line number Diff line number Diff line change
Expand Up @@ -64,32 +64,55 @@ function getSelection(node) {
start: node.selectionStart,
end: node.selectionEnd,
};
} else if (window.getSelection) {
const selection = window.getSelection();
return {
anchorNode: selection.anchorNode,
anchorOffset: selection.anchorOffset,
focusNode: selection.focusNode,
focusOffset: selection.focusOffset,
};
} else {
let win = window;
if (node.ownerDocument && node.ownerDocument.defaultView) {
win = node.ownerDocument.defaultView;
}
if (win.getSelection) {
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Likewise, when is getSelection absent?

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Likewise, in IE8

const selection = win.getSelection();
return {
anchorNode: selection.anchorNode,
anchorOffset: selection.anchorOffset,
focusNode: selection.focusNode,
focusOffset: selection.focusOffset,
};
}
}
}

/**
* Get document associated with the event target.
*
* @param {object} nativeEventTarget
* @return {Document}
*/
function getEventTargetDocument(eventTarget) {
return eventTarget.window === eventTarget
? eventTarget.document
: eventTarget.nodeType === DOCUMENT_NODE
? eventTarget
: eventTarget.ownerDocument;
}

/**
* Poll selection to see whether it's changed.
*
* @param {object} nativeEvent
* @param {object} nativeEventTarget
* @return {?SyntheticEvent}
*/
function constructSelectEvent(nativeEvent, nativeEventTarget) {
// Ensure we have the right element, and that the user is not dragging a
// selection (this matches native `select` event behavior). In HTML5, select
// fires only on input and textarea thus if there's no focused element we
// won't dispatch.
const doc = getEventTargetDocument(nativeEventTarget);

if (
mouseDown ||
activeElement == null ||
activeElement !== getActiveElement()
activeElement !== getActiveElement(doc)
) {
return null;
}
Expand Down Expand Up @@ -140,12 +163,7 @@ const SelectEventPlugin = {
nativeEvent,
nativeEventTarget,
) {
const doc =
nativeEventTarget.window === nativeEventTarget
? nativeEventTarget.document
: nativeEventTarget.nodeType === DOCUMENT_NODE
? nativeEventTarget
: nativeEventTarget.ownerDocument;
const doc = getEventTargetDocument(nativeEventTarget);
// Track whether all listeners exists for this plugin. If none exist, we do
// not extract events. See #3639.
if (!doc || !isListeningToAllDependencies('onSelect', doc)) {
Expand Down