The boolean type in TypeScript is throwing an error because it does not have any call

Currently, I am grappling with an issue in my Typescript and React Native project. The error message displayed on the console reads: "This expression is not callable. Type 'Boolean' has no call signatures." My code consists of a simple home page with two cards, each meant to navigate the user to another page upon clicking. To achieve this functionality, I decided to experiment with the useState hook for better comprehension. Below is the snippet from home.tsx:

import { Button, StyleSheet, Text, View } from "react-native"

import CardsComponent from "../../components/cards/cards"
import EcoNoticias from "../../components/EcoNoticias/EcoNoticias";
import React from "react";
import { useState } from "react";

export interface HomeComponentProps {
    
}
 
const HomeComponent: React.FC<HomeComponentProps> = () => {
    const [buttonPressed, setButtonPressed] = useState<boolean>(false);

    const handlePage = () => {
        setButtonPressed(true);
    };
    
    return (
        <>
            <View>
                <Text style={styles.title}>Hello User</Text>
                <View>
                    {() => buttonPressed(false)} ?
                    <CardsComponent>
                        <Text style={styles.textCard}>Tips</Text>
                        <Button title='Tips' onPress={() => {}} />
                    </CardsComponent>
                    <CardsComponent>
                        <Text style={styles.textCard}>Eco-Noticias</Text>
                        <Button title='Eco-Noticias' onPress={handlePage} />
                    </CardsComponent> : <EcoNoticias />
                </View>
            </View>
        </>
    );
};
const styles = StyleSheet.create({
    title: {
        fontSize: 23,
        paddingBottom: 50,
        textAlign: 'center',
    },
    textCard: {
        color: 'white',
        fontWeight: '700',
        textAlign: 'center',
        paddingBottom: 10,
    },
    buttonStyle: {
        width: '50%',
    },
});


export default HomeComponent;

The specific error occurs in the ternary if statement on line 24: "buttonPressed(false)".

Answer №1

{() => buttonPressed(false)} ?

This instruction prompts the switch back to plain javascript (instead of jsx), followed by the creation of a function with the statement () => buttonPressed(false), then switching back to jsx to display the string "?". The issue indicated by the typescript error you're encountering stems from trying to call buttonPressed as a function when it is actually a boolean.

The correct approach, based on the comments, seems to be:

{buttonPressed === false ? (
  <React.Fragment>
    <CardsComponent>
      <Text style={styles.textCard}>Tips</Text>
      <Button title="Tips" onPress={() => {}} />
    </CardsComponent>
    <CardsComponent>
      <Text style={styles.textCard}>Eco-Noticias</Text>
      <Button title="Eco-Noticias" onPress={handlePage} />
    </CardsComponent>
  </React.Fragment>
) : (
  <EcoNoticias />
)}

It's important to use <React.Fragment> when multiple elements are involved. Alternatively, you can utilize the shorthand <></> instead of

<React.Fragment></React.Fragment>

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