I have illustrated the problem in this CodePen
const Component = ({ structure }) => {
switch (structure) {
case 'nested':
return (
<div>
<AnimatedComponent />
</div>
);
case 'flat':
return
<AnimatedComponent />
;
}
};
There's some logic in AnimatedComponent that changes the styling of the Component in an animated fashion, e.g. change the background color from black to red over a duration of 1 second. The animation is started by changing a color class on AnimatedComponent. There is CSS to handle the animation given the changed class.
When changing the DOM structure from nested to flat, the HTML element is destroyed and recreated, the transition starting state is lost (aka the browser doesn't know which class was set before because the element was newly created).
What I want React to do is to change the DOM structure with moving elements in new positions, not destroying and recreating them.
Is this possible?
I tried to use the key props on <AnimatedComponent />, but it only fixes the flash of DOM change. Animation is skipped. See Codepen. Thanks Thomas Rooney for this suggestion.
Can I tell React to apply the class changes just one tick after the position of the DOM element was changed?
Can I tell React to apply the class changes just one tick after the position of the DOM element was changed?
Yes, this is precisely what the setTimeout function is for. Copying your second example, where you fixed the flickering, wrapping your color action dispatch with setTimeout (with no time value, which defaults to 0), seems to fix your issue.
onColorClick: () => {
setTimeout(() => {
dispatch({type: 'TOGGLE_COLOR'})
})
},
codepen
Update: I've noticed it's a bit more reliable to add some time before the color change (second argument in setTimeout, (fn, ms). I believe this is because setState is also happening asynchronously.
onColorClick: () => {
setTimeout(() => {
dispatch({type: 'TOGGLE_COLOR'})
}, 100) <-- play around with this value
},
Related
i've made this banner like screen that appears when my site is loaded, but here's the thing, i don't want no scrollbar while this opening animation it's happening, i only want to show the other components (the scrollbar and the whole site) once the gsap animation finishes, how could i proceed? thanks! (i tried to create a function to control those global elements, is it a way?)
So if I understand correctly you need the Banner to be displayed until the site is loaded. Maybe you are making some API calls or in general, you are planning to show the banner for let's say 3 sec and post that you want your actual components to be displayed.
You can try below approch:
export const APP = (): JSX.Element => {
const [isAnimationInProgress, SetAnimationState] = React.useState(true);
React.useEffect(() => {
// You can have your page load API calls done here
// Or wait for 'X' seconds
// Post that set the AnimationState to false to render actual components
setAnimationState(false);
})
return (
{
isAnimationInProgress && <Banner />
}
{
!isAnimationInProgress && <ActualComponent />
}
)
}
Regarding scrollbars, including overflow: hidden; in style for the banner should do the work if you are getting scrollbars for the Banner component.
On this sandbox, I've recreated the classic sliding-puzzle game.
On my GameBlock component, I'm using a combination of css transform: translate(x,y) and transition: transform in order to animate the sliding game-pieces:
const StyledGameBlock = styled.div<{
index: number;
isNextToSpace: boolean;
backgroundColor: string;
}>`
position: absolute;
display: flex;
justify-content: center;
align-items: center;
width: ${BLOCK_SIZE}px;
height: ${BLOCK_SIZE}px;
background-color: ${({ backgroundColor }) => backgroundColor};
${({ isNextToSpace }) => isNextToSpace && "cursor: pointer"};
${({ index }) => css`
transform: translate(
${getX(index) * BLOCK_SIZE}px,
${getY(index) * BLOCK_SIZE}px
);
`}
transition: transform 400ms;
`;
Basically, I'm using the block's current index on the board in order to calculate it's x and y values which change the transform: translate value of the block when it's being moved.
While this does manage to trigger a smooth transition when sliding the block to the top, to the right and to the left - for some reason, sliding the block from top to bottom doesn't transition smoothly.
Any ideas what's causing this exception?
React, lists and keys
What you're seeing is the result of a mount/unmount of the <GameBlock /> components.
Although you're passing a key prop to the component, React is unsure that you're still rendering the same element.
If I have to guess why react is uncertain, I would put the culprit at:
Changing the array sort with:
const previousSpace = gameBlocks[spaceIndex];
gameBlocks[spaceIndex] = gameBlocks[index];
gameBlocks[index] = previousSpace;
having different virtual DOM results using the conditional on isSpace:
({ correctIndex, currentIndex, isSpace, isNextToSpace }) => isSpace ? null : ( <GameBlock ....
Usually in applications, we don't mind a re-mount since it's pretty fast. When we attach an animation, we don't want any re-mounts since they mess with the css-transitions.
in order for react to be certain it's the same node and no re-mount is needed. we should take care that; between renders; the virtual dom stays mostly the same.
we can achieve that not doing anything fancy in the render of the list, and passing down the same keys between renders.
Pass isSpace down
Instead of changing the the rendered DOM nodes, we want the list render to always return an equal amount of nodes, with the exact same keys for each Node, in the same order.
simply passing 'isSpace' down and styling as display:none; should do the trick.
<GameBlock
...
isSpace={isSpace}
...
>
const StyledGameBlock = styled.div<{ ....}>`
...
display: ${({isSpace})=> isSpace? 'none':'flex'};
...
`;
Making sure to not change the arraysort
React considers the gameBlocks array to be modified, the keys are in a different order. Thus triggering unmount/mount of the rendered <GameBlock/> components.
We can make sure that react considers this array to be unmodified, by only changing the properties of the items in the list and not the sort itself.
in your case, we can leave all properties as is, only changing the currentIndex for the blocks that are moved/swapped with each other.
const onMove = useCallback(
(index) => {
const newSpaceIndex = gameBlocks[index].currentIndex; // the space will get the current index of the clicked block.
const movedBlockNewIndex = gameBlocks[spaceIndex].currentIndex; // the clicked block will get the index of the space.
setState({
spaceIndex: spaceIndex, // the space will always have the same index in the array.
gameBlocks: gameBlocks.map((block) => {
const isMovingBlock = index === block.correctIndex; // check if this block is the one that was clicked
const isSpaceBlock =
gameBlocks[spaceIndex].currentIndex === block.currentIndex; // check if this block is the space block.
let newCurrentIndex = block.currentIndex; // most blocks will stay in their spot.
if (isMovingBlock) {
newCurrentIndex = movedBlockNewIndex; // the moving block will swap with the space.
}
if (isSpaceBlock) {
newCurrentIndex = newSpaceIndex; // the space will swap with the moving block
}
return {
...block,
currentIndex: newCurrentIndex,
isNextToSpace: getIsNextToSpace(newCurrentIndex, newSpaceIndex)
};
})
});
},
[gameBlocks, spaceIndex]
);
...
// we have to be sure to call onMove the with the index of the clicked block.
() => onMove(correctIndex)
The only things we've changed are is the currentIndex of the clicked block and the space.
sandbox:
sandbox example based on your provided sandbox.
closing thoughts: I think your code was easy to read and understand, good job on that!
Additionally to the excellent answer and explanations #Lars provided, I wanted to share visual proof that certain <GameBlock /> components are indeed unmounted or changed in order, causing the hiccup in the CSS animation.
As you can see, when focussing one of the blocks and sliding down, the element changes its position in the DOM.
I have an application where I'm using Material UI and its theme provider (using JSS).
I'm now incorporating fullcalendar-react, which isn't really a fully fledged React library - it's just a thin React component wrapper around the original fullcalendar code.
That is to say, that I don't have access to things like render props to control how it styles its elements.
It does however, give you access to the DOM elements directly, via a callback that is called when it renders them (eg. the eventRender method).
Here's a basic demo sandbox.
Now what I'm wanting to do is make Full Calendar components (eg, the buttons) share the same look and feel as the rest of my application.
One way to do this, is that I could manually override all of the styles by looking at the class names it's using and implementing the style accordingly.
Or - I could implement a Bootstrap theme - as suggested in their documentation.
But the problem with either of these solutions, is that that:
It would be a lot of work
I would have synchronisation problems, if I made changes to my MUI theme and forgot to update the calendar theme they would look different.
What I would like to do is either:
Magically convert the MUI theme to a Bootstrap theme.
Or create a mapping between MUI class names and the calendar class names, something like:
.fc-button = .MuiButtonBase-root.MuiButton-root.MuiButton-contained
.fc-button-primary= .MuiButton-containedPrimary
I wouldn't mind having to massage the selectors etc to make it work (ie. For example - MUI Buttons have two internal spans, whereas Full Calendar have just one). It's mostly about when I change the theme - don't want to have to change it in two places.
Using something like Sass with its #extend syntax would is what I have in mind. I could create the full-calendar CSS with Sass easily enough - but how would Sass get access to the MuiTheme?
Perhaps I could take the opposite approach - tell MUI 'Hey these class names here should be styled like these MUI classes'.
Any concrete suggestions on how I would solve this?
Here is my suggestion (obviously, it's not straight forward). Take the styles from the MUI theme and generate style tag based on it using react-helmet. To do it event nicely, I created a "wrapper" component that do the map. I implemented only the primary rule but it can be extended to all the others.
This way, any change you will do in the theme will affect the mapped selectors too.
import React from "react";
import { Helmet } from "react-helmet";
export function MuiAdapter({ theme }) {
if (!theme.palette) {
return <></>;
}
return (
<Helmet>
<style type="text/css">{`
.fc-button-primary {
background: ${theme.palette.primary.main}
}
/* more styles go here */
`}</style>
</Helmet>
);
}
And the use of the adapter
<MuiAdapter theme={theme} />
Working demo: https://codesandbox.io/s/reverent-mccarthy-3o856
You could create a mapping between MUI class names and the calendar class names by going through ref's. It's possible that this is not what some would call "best practice"...but it's a solution :). Note that I updated your component from a functional component to a class component, but you could accomplish this with hooks in a functional component.
Add refs
Add a ref to the MUI element you want to set as a reference, in your case the Button.
<Button
color="primary"
variant="contained"
ref={x => {
this.primaryBtn = x;
}}
>
And a ref to a wrapping div around the component you want to map to. You can't add it directly to the component since that wouldn't give us access to children.
<div
ref={x => {
this.fullCal = x;
}}
>
<FullCalendar
...
/>
</div>
Map classes
From componentDidMount() add whatever logic you need to target the correct DOM node (for your case, I added logic for type and matchingClass). Then run that logic on all FullCalendar DOM nodes and replace the classList on any that match.
componentDidMount() {
this.updatePrimaryBtns();
}
updatePrimaryBtns = () => {
const children = Array.from(this.fullCal.children);
// Options
const type = "BUTTON";
const matchingClass = "fc-button-primary";
this.mapClassToElem(children, type, matchingClass);
};
mapClassToElem = (arr, type, matchingClass) => {
arr.forEach(elem => {
const { tagName, classList } = elem;
// Check for match
if (tagName === type && Array.from(classList).includes(matchingClass)) {
elem.classList = this.primaryBtn.classList.value;
}
// Run on any children
const next = elem.children;
if (next.length > 0) {
this.mapClassToElem(Array.from(next), type, matchingClass);
}
});
};
This is maybe a little heavy handed, but it meets your future proof requirement for when you updated update Material UI. It would also allow you to alter the classList as you pass it to an element, which has obvious benefits.
Caveats
If the 'mapped-to' component (FullCalendar) updated classes on the elements you target (like if it added .is-selected to a current button) or adds new buttons after mounting then you'd have to figure out a way to track the relevant changes and rerun the logic.
I should also mention that (obviously) altering classes might have unintended consequences like a breaking UI and you'll have to figure out how to fix them.
Here's the working sandbox: https://codesandbox.io/s/determined-frog-3loyf
I'm trying to create an App with a global dictionary; so that when a word that appears in the dictionary is hovered than a small box appears next to it with a definition.
The problem is that the text in the dictionary can appear any where on the screen, and I need to align the floating box so that it will not be displayed out side of the screen
Similar to this
only that I need to be able to style the floating box, like this
Note that the box display outside of the screen:
I tired to use ui material ToolTip
but it throws
TypeError
Cannot read property 'className' of undefined
I solved a similar problem before with jQuery, where I dynamically calculated the position of the box, relative to the screen and the current element.
but I don't know how to do it in react, mainly since I don't know how to get the position of the current element dynamical.
Please help
To give an idea where to start, have a look at useCallback and refs for React. With the given information from node.getBoundingClientRect(), you could calculate if your tooltip is outside the visible area of the browser.
// edit: useCallback won't work in this case, because the visibility is triggered by a css hover and the dimensions are not yet available for the hidden tooltip. Here is a possible solution with useRef and use useEffect though:
function ToolTip({ word, description }) {
const [left, setLeft] = useState(0);
const [hover, setHover] = useState(false);
const ref = useRef(null);
useEffect(() => {
if (ref.current) {
const { right } = ref.current.getBoundingClientRect();
if (window.innerWidth < right) {
setLeft(window.innerWidth - right);
}
}
}, [hover]);
return (
<span
desc={description}
className="dashed"
onMouseEnter={() => setHover(true)}
onMouseLeave={() => {
setHover(false);
setLeft(0);
}}
>
{word}
<div ref={ref} className="explain" style={{ left }}>
<h2>{word}</h2>
{description}
</div>
</span>
);
}
Codepen example: https://codesandbox.io/s/lk60yj307
I was able to do it with
https://www.npmjs.com/package/#syncfusion/ej2-react-popups
But I still wonder what is the correct way to do it in code.
I am writhing Angular 2+ unit test with TestBed.
Scenario, I want to verify my component, that the color of a pseudo element.
component.ts
label::before {
right: 0;
background-color: red;
}
#Component({
selector: 'app-test',
template: `
<div><label>a label</label></div>
`,
styleUrls: ['./test.component.scss'],
})
export class TestComponent {
}
so when I write unit test, I want to verify the pseudo element background color
beforeEach(() => {
fixture = TestBed.createComponent(TestComponent);
component = fixture.componentInstance;
fixture.detectChanges();
});
it('should set background color', () => {
const ele = fixture.debugElement.query(By.css('label::before')).nativeElement; // error here
// not sure how to use by.css to locate on the pseudo element
expect(ele.backgroundColor).toBe('....');
});
I would suggest writing your test in a different manner.
Fixture is of type ComponentFixture<T> where T is the component you are trying to access. The debugElement property has two properties that you are normally interested In when writing a test componentInstance and nativeElement
ComponentInstance is your component ts file. It's your class declaration in a sense.
NativeElement as the name suggests is the mark-up or your template
I don't think it's possible to do it the way you suggested.
However you could try
const color = window.getComputedStyle(fixture.debugElement.nativeElement.querySelector('label'), ':after').getPropertyValue('background-color');
This will give you a rgb result so for red it would be rgb(255,0,0)
I got this from: How to get pseudo element?
Try this and see if it works. It's not great that we had to access the window element inside of our test but it might solve your issue. Possibly create a better test without having to access the window api i would suggest.