在 CSS 中反转动画

Question

我正在尝试做的事情：当在搜索栏中输入内容时，未搜索的用户名必须淡出并消失（效果很好），我试图在搜索栏中的字母被删除或搜索栏被清除。

App.js

import React, { useState, useEffect } from "react";
import SearchBar from "./SearchBar";
import "./App.scss";

const users = [
  { name: "Jack", id: "1" },
  { name: "Lisa", id: "2" },
  { name: "Peter", id: "3" },
  { name: "Roman", id: "4" },
  { name: "Sarah", id: "5" },
  { name: "Eric", id: "6" },
  { name: "Fiora", id: "7" },
];

function App() {
  const [searchValue, setSearchValue] = useState("");
  const [searchFilter, setSearchFilter] = useState(users);

  return (
    <div className="App">
      <h2>Search</h2>
      <SearchBar onSearch={setSearchValue} value={searchValue} />
      <ul className="users">
        {searchFilter.map((user) => {
          let classname =
            user.name.toLowerCase().indexOf(searchValue.toLowerCase()) === -1 &&
            "hide";

          return (
            <li className={`user ${classname}`} key={user.id}>
              {user.name}
            </li>
          );
        })}
      </ul>
    </div>
  );
}

export default App;

搜索栏.js

import React from "react";

function SearchBar(props) {
  const handleSearch = (e) => {
    props.onSearch(e.target.value);
  };

  return <input type="text" onChange={handleSearch} value={props.value} />;
}

export default SearchBar;

App.scss

.user {
  list-style: none;
}

.hide {
  animation: fade-out 1s ease-out forwards;
}

@keyframes fade-out {
  0% {
    opacity: 1;
  }

  50% {
    opacity: 0;
    height: inherit;
    padding: inherit;
  }

  100% {
    opacity: 0;
    height: 0;
    padding: 0;
  }
}

所以基本上我只是想在用户删除搜索栏中的字母时反转动画。

Answer 1

您可以像使用hide 一样使用show 类

在 App.js 中

let classname = user.name.toLowerCase().indexOf(searchValue.toLowerCase()) === -1 ? "hide" : "show";

在 App.scss 中

.show {
  animation: fade-in 1s ease-out forwards;
}

@keyframes fade-in {

  0% {
    opacity: 0;
    height: 0;
    padding: 0;
  }

  50% {
    opacity: 0;
    height: inherit;
    padding: inherit;
  }

  100% {
    opacity: 1;
  }
}

你可以走了。

Answer 2

你可以只反转动画定义，检查这个codesandbox：

CSS：

.show {
  animation: fade-in 1s ease-out forwards;
}

@keyframes fade-in {
  0% {
    opacity: 0;
    height: 0;
    padding: 0;
  }

  50% {
    opacity: 0;
    height: inherit;
    padding: inherit;
  }

  100% {
    opacity: 1;
  }
}

在<App /> 组件内部：（检查隐藏/显示类）：

function App() {
  const [searchValue, setSearchValue] = useState("");
  const [searchFilter, setSearchFilter] = useState(users);

  return (
    <div className="App">
      <h2>Search</h2>
      <SearchBar onSearch={setSearchValue} value={searchValue} />
      <ul className="users">
        {searchFilter.map(user => {
          let classname =
            user.name.toLowerCase().indexOf(searchValue.toLowerCase()) === -1
              ? "hide"
              : "show"; // <--- HERE we switch for show/hide class.

          return (
            <li className={`user ${classname}`} key={user.id}>
              {user.name}
            </li>
          );
        })}
      </ul>
    </div>
  );
}