[0,1,2,3].map 工作正常,array.map 给出奇怪的结果
[0,1,2,3].map works fine, array.map gives strange results
我正在使用成帧器运动,我正在尝试实现交错,以便每个下一个 child 都有一些不错的延迟。有一行关键代码,当我用 recipes.map
替换 [0, 1, 2, 3].map
时,突然所有 children 都被视为一个巨大的块,它们不会交错。
只要看看这个demo,您一定会明白我的意思。这段代码有什么问题?我快疯了:)
function App() {
const request = `https://www.themealdb.com/api/json/v1/1/search.php?s=chicken`;
const [recipes, setRecipes] = useState([]);
useEffect(() => {
getRecipes();
}, []);
const getRecipes = async () => {
const response = await fetch(request);
const data = await response.json();
setRecipes(data.meals);
console.log(data.meals);
};
const container = {
hidden: { opacity: 1, scale: 0 },
visible: {
opacity: 1,
scale: 1,
transition: {
when: "beforeChildren",
staggerChildren: 0.5
}
}
};
const item = {
hidden: { x: 100, opacity: 0 },
visible: {
x: 0,
opacity: 1
}
};
return (
<div className="App">
<motion.ul variants={container} initial="hidden" animate="visible">
{[0, 1, 2, 3].map(recipe => (
<motion.li key={recipe.idMeal} variants={item}>
<RecipeCard title={recipe.strMeal} />
</motion.li>
))}
</motion.ul>
<motion.ul variants={container} initial="hidden" animate="visible">
{recipes.map(recipe => (
<motion.li key={recipe.idMeal} variants={item}>
<RecipeCard title={recipe.strMeal} />
</motion.li>
))}
</motion.ul>
</div>
);
}
这有点棘手,但您只需要在项目可用时设置动画:
animate={recipes.length > 0 && "visible"}
那是因为在第一次渲染时,您实际上为一个空数组设置了动画。
animate="visible"
然后,当您在异步调用后更新 recipes
时,您不会再次触发动画。
const container = {
hidden: { opacity: 1, scale: 0 },
visible: {
opacity: 1,
scale: 1,
transition: {
staggerChildren: 0.5
}
}
};
const item = {
hidden: { x: 100, opacity: 0 },
visible: {
x: 0,
opacity: 1
}
};
const request = `https://www.themealdb.com/api/json/v1/1/search.php?s=chicken`;
function App() {
const [recipes, setRecipes] = useState([]);
useEffect(() => {
const getRecipes = async () => {
const response = await fetch(request);
const data = await response.json();
setRecipes(data.meals);
console.log(data.meals);
};
getRecipes();
}, []);
return (
<div className="App">
<motion.ul
variants={container}
initial="hidden"
animate={recipes.length > 0 && "visible"}
>
{recipes.map(recipe => (
<motion.li key={recipe.idMeal} variants={item}>
<RecipeCard title={recipe.strMeal} />
</motion.li>
))}
</motion.ul>
</div>
);
}
我正在使用成帧器运动,我正在尝试实现交错,以便每个下一个 child 都有一些不错的延迟。有一行关键代码,当我用 recipes.map
替换 [0, 1, 2, 3].map
时,突然所有 children 都被视为一个巨大的块,它们不会交错。
只要看看这个demo,您一定会明白我的意思。这段代码有什么问题?我快疯了:)
function App() {
const request = `https://www.themealdb.com/api/json/v1/1/search.php?s=chicken`;
const [recipes, setRecipes] = useState([]);
useEffect(() => {
getRecipes();
}, []);
const getRecipes = async () => {
const response = await fetch(request);
const data = await response.json();
setRecipes(data.meals);
console.log(data.meals);
};
const container = {
hidden: { opacity: 1, scale: 0 },
visible: {
opacity: 1,
scale: 1,
transition: {
when: "beforeChildren",
staggerChildren: 0.5
}
}
};
const item = {
hidden: { x: 100, opacity: 0 },
visible: {
x: 0,
opacity: 1
}
};
return (
<div className="App">
<motion.ul variants={container} initial="hidden" animate="visible">
{[0, 1, 2, 3].map(recipe => (
<motion.li key={recipe.idMeal} variants={item}>
<RecipeCard title={recipe.strMeal} />
</motion.li>
))}
</motion.ul>
<motion.ul variants={container} initial="hidden" animate="visible">
{recipes.map(recipe => (
<motion.li key={recipe.idMeal} variants={item}>
<RecipeCard title={recipe.strMeal} />
</motion.li>
))}
</motion.ul>
</div>
);
}
这有点棘手,但您只需要在项目可用时设置动画:
animate={recipes.length > 0 && "visible"}
那是因为在第一次渲染时,您实际上为一个空数组设置了动画。
animate="visible"
然后,当您在异步调用后更新 recipes
时,您不会再次触发动画。
const container = {
hidden: { opacity: 1, scale: 0 },
visible: {
opacity: 1,
scale: 1,
transition: {
staggerChildren: 0.5
}
}
};
const item = {
hidden: { x: 100, opacity: 0 },
visible: {
x: 0,
opacity: 1
}
};
const request = `https://www.themealdb.com/api/json/v1/1/search.php?s=chicken`;
function App() {
const [recipes, setRecipes] = useState([]);
useEffect(() => {
const getRecipes = async () => {
const response = await fetch(request);
const data = await response.json();
setRecipes(data.meals);
console.log(data.meals);
};
getRecipes();
}, []);
return (
<div className="App">
<motion.ul
variants={container}
initial="hidden"
animate={recipes.length > 0 && "visible"}
>
{recipes.map(recipe => (
<motion.li key={recipe.idMeal} variants={item}>
<RecipeCard title={recipe.strMeal} />
</motion.li>
))}
</motion.ul>
</div>
);
}