Is it possible to use if...else... statements in React render functions?
P粉760675452
P粉760675452 2023-08-23 18:27:14
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<p>Basically, I have a react component whose <code>render()</code> function body is as follows: (This is my ideal one, which means it doesn't work at the moment)< /p> <pre class="brush:js;toolbar:false;">render(){ return ( <div> <Element1/> <Element2/> // note: logic only, code does not work here if (this.props.hasImage) <ElementWithImage/> else <ElementWithoutImage/> </div> ) } </pre> <p><br /></p>
P粉760675452
P粉760675452

reply all(2)
P粉288069045

There is actually a way to do exactly what the OP asked for. Just render and call the anonymous function like this:

render () {
  return (
    <div>
      {(() => {
        if (someCase) {
          return (
            <div>someCase</div>
          )
        } else if (otherCase) {
          return (
            <div>otherCase</div>
          )
        } else {
          return (
            <div>catch all</div>
          )
        }
      })()}
    </div>
  )
}
P粉176980522

Not exactly the same, but there is a workaround. There is a section about conditional rendering in the React documentation that you should take a look at. The following is an example of what you can do using inline if-else.

render() {
  const isLoggedIn = this.state.isLoggedIn;
  return (
    <div>
      {isLoggedIn ? (
        <LogoutButton onClick={this.handleLogoutClick} />
      ) : (
        <LoginButton onClick={this.handleLoginClick} />
      )}
    </div>
  );
}

You can also handle it inside the render function, but before returning jsx.

if (isLoggedIn) {
  button = <LogoutButton onClick={this.handleLogoutClick} />;
} else {
  button = <LoginButton onClick={this.handleLoginClick} />;
}

return (
  <div>
    <Greeting isLoggedIn={isLoggedIn} />
    {button}
  </div>
);

Also worth mentioning is what ZekeDroid brought up in the comments. If you are just checking a condition and don't want to render a specific piece of code that doesn't meet the condition, you can use the && operator.

return (
    <div>
      <h1>Hello!</h1>
      {unreadMessages.length > 0 &&
        <h2>
          You have {unreadMessages.length} unread messages.
        </h2>
      }
    </div>
  );
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