if-else statement inside jsx: ReactJS

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.

Answers:

Answer

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>
    )
}
Answer

I find this way is the nicest:

{this.state.yourVariable === 'news' && <Text>{data}<Text/>}
Answer

I do like this and its working fine.

constructor() {
   super();

   this.state ={
     status:true
   }
}

render() {
   return( 

     { this.state.status === true ?
           <TouchableHighlight onPress={()=>this.hideView()}>
             <View style={styles.optionView}>
               <Text>Ok Fine :)</Text>
             </View>
          </TouchableHighlight>
           :
           <Text>Ok Fine.</Text>
     }
  );
}

hideView(){
  this.setState({
    home:!this.state.status
  });
}
Answer

There's a Babel plugin that allows you to write conditional statements inside JSX without needing to escape them with JavaScript or write a wrapper class. It's called JSX Control Statements:

<View style={styles.container}>
  <If condition={ this.state == 'news' }>
    <Text>data</Text>
  </If>
</View>

It takes a bit of setting up depending on your Babel configuration, but you don't have to import anything and it has all the advantages of conditional rendering without leaving JSX which leaves your code looking very clean.

Answer

You can do this. Just don't forget to put "return" before your JSX component.

Example:

render() {
    if(this.state.page === 'news') {
        return <Text>This is news page</Text>;
    } else {
        return <Text>This is another page</Text>;
    }
}

Example to fetch data from internet:

import React, { Component } from 'react';
import {
    View,
    Text
} from 'react-native';

export default class Test extends Component {
    constructor(props) {
        super(props);

        this.state = {
            bodyText: ''
        }
    }

    fetchData() {
        fetch('https://example.com').then((resp) => {
            this.setState({
                bodyText: resp._bodyText
            });
        });
    }

    componentDidMount() {
        this.fetchData();
    }

    render() {
        return <View style={{ flex: 1 }}>
            <Text>{this.state.bodyText}</Text>
        </View>
    }
}
Answer

You can't provide if-else condition in the return block, make use of ternary block, also this.state will be an object, you shouldn't be comparing it with a value, see which state value you want to check, also return returns only one element, make sure to wrap them in a View

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

     )
}
Answer

What about switch case instead of if-else

  render() {
    switch (this.state.route) {
      case 'loginRoute':
        return (
            <Login changeRoute={this.changeRoute}
              changeName={this.changeName}
              changeRole={this.changeRole} />
        );
      case 'adminRoute':
        return (
            <DashboardAdmin
              role={this.state.role}
              name={this.state.name}
              changeRoute={this.changeRoute}
            />
        );
    }
Answer
 render() {
     return (   
         <View style={styles.container}>
         (() => {                                                       
             if (this.state == 'news') {
                return  <Text>data</Text>
            }
            else 
             return  <Text></Text>
        })()
         </View>
     )
 }

https://react-cn.github.io/react/tips/if-else-in-JSX.html

Answer

For this we can use ternary operator or if there is only one condition then "&&" operator .Like this:-

//This is for if else

render() {

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

}

//This is only for if or only for one condition

render() {

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

}

Answer

In two ways we can solve this problem:

  1. Write a else condition by adding just empty <div> element.
  2. or else return null.
render() {
    return (   
        <View style={styles.container}>
            if (this.state == 'news'){
                return (
                    <Text>data</Text>
                );
            }
            else {
                 <div> </div>
            }

        </View>
    )
}
Answer

You can achieve what you are saying by using Immediately Invoked Function Expression (IIFE)

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

Here is the working example:

Edit awesome-yalow-eb2nu

But, In your case, you can stick with the ternary operator

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