if-else statement inside jsx: ReactJS

user8026867 picture user8026867 · May 18, 2017 · Viewed 213.3k times · Source

I need to change render function and run some sub render function when a specific state given,

For example:

render() {
    return (   
        <View style={styles.container}>
            if (this.state == 'news'){
                return (
                    <Text>data</Text>
                )
            }
        </View>
    )
}

How can I implement that without changing scenes, I will use tabs to change content dynamically.

Answer

Mayank Shukla picture Mayank Shukla · May 18, 2017

As per DOC:

if-else statements don't work inside JSX. This is because JSX is just syntactic sugar for function calls and object construction.

Basic Rule:

JSX is fundamentally syntactic sugar. After compilation, JSX expressions become regular JavaScript function calls and evaluate to JavaScript objects. We can embed any JavaScript expression in JSX by wrapping it in curly braces.

But only expressions not statements, means directly we can not put any statement (if-else/switch/for) inside JSX.


If you want to render the element conditionally then use ternary operator, like this:

render() {
    return (   
        <View style={styles.container}>
            {this.state.value == 'news'? <Text>data</Text>: null }
        </View>
    )
}

Another option is, call a function from jsx and put all the if-else logic inside that, like this:

renderElement(){
   if(this.state.value == 'news')
      return <Text>data</Text>;
   return null;
}

render() {
    return (   
        <View style={styles.container}>
            { this.renderElement() }
        </View>
    )
}