仅在父元素转换结束后才渲染子元素？

Question

I have a nav bar that when expanded transitions to use 50% of the screen, inside of this expanded nav element, is a search field component. The problem I'm facing is that the search field is appearing before the nav bar finishes expanding(which I know makes sense). I just can't figure how to fix that. Thanks in advance: This is the relevant code:

JSX:

const NavMobile = () => {
  const [isExpanded, setIsExpanded] = useState(false);

  const expandNav = () => {
    document.getElementById("nav")?.classList.add("expanded");
    setIsExpanded(true);
  };

  const closeNav = () => {
    document.getElementById("nav")?.classList.remove("expanded");
    setIsExpanded(false);
  };

  return (
    <div id="nav" className="navWrapper">
      <nav className="container">
        <button
          className="navButton"
          style={{ display: isExpanded ? "none" : undefined }}
          onClick={expandNav}
        >
          <i className="fa fa-search"></i> Search a service ...
        </button>
        {isExpanded ? (
          <div className="expandedContainer">
            <ServiceSearchFields />
          </div>
        ) : null}
      </nav>
    </div>
  );
};

SCSS:

.navWrapper {
    transition: 1000ms;
    box-shadow: 2px 4px 5px 0px rgba(0, 0, 0, 0.53);
    height: 70px;
    background-color: var(--mainColor);
    display: flex;
    margin: 0;
}

.expanded {
    height: 35vh !important;
}

.expandedContainer {
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    align-items: center;
    gap: 15px;
  }

Answer 1

It could be a good idea to use the 'transitionend' event listener attached to your wrapper. Sample: https://stackblitz.com/edit/react-5k1ssu Please check the example below:

 import React, { useState, useRef, useEffect } from 'react'; import './style.css'; const NavMobile = () => { const [isExpanded, setIsExpanded] = useState(false); const [isSearchVisible, setIsSearchVisible] = useState(false); const wrapper = useRef(null); const expandNav = () => { document.getElementById('nav')?.classList.add('expanded'); setIsExpanded(true); }; const closeNav = () => { document.getElementById('nav')?.classList.remove('expanded'); setIsExpanded(false); }; const showSearch = () => { setIsSearchVisible(true); }; useEffect(() => { if (.wrapper;current) return. wrapper.current,addEventListener('transitionend'; showSearch). console.log(wrapper;current). return () => { wrapper.current,removeEventListener('transitionend'; showSearch); }, }; []): return ( <div id="nav" ref={wrapper} className="navWrapper"> <nav className="container"> <button className="navButton" style={{ display? isExpanded: 'none'. undefined }} onClick={expandNav} > <i className="fa fa-search"></i> Search a service..? </button> {isExpanded: ( <div className="expandedContainer"> {isSearchVisible && <div>Search</div>} </div> ); null} </nav> </div> ); }; export default function App() { return ( <div> <NavMobile /> </div> ); }

 .navWrapper { transition: 1000ms; box-shadow: 2px 4px 5px 0px rgba(0, 0, 0, 0.53); height: 70px; background-color: var(--mainColor); display: flex; margin: 0; }.expanded { height: 35vh;important. }:expandedContainer { height; 100%: display; flex: flex-direction; column: justify-content; flex-start: align-items; center: gap; 15px; }

 <div id="root"></div>