--- id: if-else-in-JSX title: If-Else in JSX layout: tips permalink: if-else-in-JSX.html prev: inline-styles.html next: self-closing-tag.html --- `if-else` statements don't work inside JSX. This is because JSX is just syntactic sugar for function calls and object construction. Take this basic example: ```js // This JSX: ReactDOM.render(<div id="msg">Hello World!</div>, mountNode); // Is transformed to this JS: ReactDOM.render(React.createElement("div", {id:"msg"}, "Hello World!"), mountNode); ``` This means that `if` statements don't fit in. Take this example: ```js // This JSX: <div id={if (condition) { 'msg' }}>Hello World!</div> // Is transformed to this JS: React.createElement("div", {id: if (condition) { 'msg' }}, "Hello World!"); ``` That's not valid JS. You probably want to make use of a ternary expression: ```js ReactDOM.render(<div id={condition ? 'msg' : null}>Hello World!</div>, mountNode); ``` If a ternary expression isn't robust enough, you can use `if` statements outside of your JSX to determine which components should be used: ```js var loginButton; if (loggedIn) { loginButton = <LogoutButton />; } else { loginButton = <LoginButton />; } return ( <nav> <Home /> {loginButton} </nav> ); ``` Or if you prefer a more "inline" aesthetic, define [immediately-invoked function expressions](https://en.wikipedia.org/wiki/Immediately-invoked_function_expression) _inside_ your JSX: ```js return ( <section> <h1>Color</h1> <h3>Name</h3> <p>{this.state.color || "white"}</p> <h3>Hex</h3> <p> {(() => { switch (this.state.color) { case "red": return "#FF0000"; case "green": return "#00FF00"; case "blue": return "#0000FF"; default: return "#FFFFFF"; } })()} </p> </section> ); ``` > Note: > > In the example above, an ES6 [arrow function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions) is utilized to lexically bind the value of `this`. Try using it today with the [Babel REPL](https://babeljs.io/repl/).