React native js. nothing shows when pressing the start button - javascript

I am trying to show or print the duration (timer) when the button start is pressed, but nothing is showing after pressing start. I tried doing Button instead of TouchableOpacity, but still, nothing changed.
class Timer extends Component {
constructor(props){
super(props)
this.state = {
count: 0
}
}
render () {
const {count} = this.state
return (
<ScrollView>
<SafeAreaView style={styles.container}>
<View style={styles.textInputContainer}>
<Text style={styles.txtHello}>Press start when ready</Text>
<View style={styles.sep}>
</View>
<TouchableOpacity style={styles.button}
onPress={ () =>
<View style={styles.textInputContainer}>
<Text>
<h2> Duration: {count}</h2>
</Text>
</View>
}
>
<Text>start</Text>
</TouchableOpacity>
</View>
</SafeAreaView>
</ScrollView>
)
}
componentDidMount(){
this.myInterval = setInterval(()=>{
this.setState({
count: this.state.count + 1
})
}, 1000)
}
}

I don't think this is a right way to do it in React. What you would like to do is set a isVisible state, change it with your onPress props in Button/TouchableOpacity and finally conditionally show the view you want to display based on that isVisible variable. Something like this:
class Timer extends Component {
constructor(props){
super(props)
this.state = {
isVisisble:false;
}
}
render(){
return(
<View>
<TouchableOpacity
onPress={ () => this.setState((prevState)=>{isVisible:!prevState.isVisible})}
>
<Text>start</Text>
</TouchableOpacity>
{this.state.isVisible && <View></View>} <- Conditional View here
</View>
)}

Related

Natigate to different screes within same page in React Native

I have made a main screen in which I have added three button in the header, on pressing I want to open three different screens respectively but its not working.
Here's what I've tried:
constructor(props) {
super(props);
this.state = {
initialstate: 0, //Setting initial state for screens
};
}
render(){
return(
<View style={styles.container}>
<TouchableOpacity onPress={() => this.setState({ initialstate: 0})}>
<Image source={require('../../assets/add.png')}
resizeMode="contain"/>
</TouchableOpacity>
<TouchableOpacity onPress={() => this.setState({ cardstate: 1})}>
<Image source={require('../../assets/request.png')}
resizeMode="contain"/>
</TouchableOpacity>
<TouchableOpacity onPress={() => this.setState({ cardstate: 2})}>
<Image source={require('../../assets/send.png')}
resizeMode="contain"/>
</TouchableOpacity>
{this.state.initialstate == 0 ? ( <RequestComp/> ) : ( <TopUpComp/> ) } //Over Here when I use the Third Screen like " : <SendComp/> " it gives me JXS error says "EXPECTED }"
</View>
The first problem is that you have an initialState state variable that is only updated by the first buttons and the other two are setting cardState so even if the ternary statement was formatted correctly it wouldn't have worked either way
But aside from this problem I don't recommend using a ternary for what you're trying to do, because the conditions become difficult to read.
There are multiple ways of doing this, but I like the approach of the accepted answer here React render various components based on three logic paths). The idea is to create an object that holds a mapping of strings to components. Then you can conditionally render an item based on the current key value.
Here's an example of how you could refactor your code to use this approach:
const tabComponents = {
request: <RequestComp />,
topUp: <TopUpComp />,
send: <SendComp />,
};
class CustomTabs extends React.Component {
constructor(props) {
super(props);
this.state = {
cardstate: 'request', // Setting initial state for screens
};
}
render() {
return (
<View style={styles.container}>
<TouchableOpacity
onPress={() => this.setState({ cardstate: 'request' })}>
// Button content...
</TouchableOpacity>
<TouchableOpacity onPress={() => this.setState({ cardstate: 'topUp' })}>
// Button content...
</TouchableOpacity>
<TouchableOpacity
onPress={() => this.setState({ cardstate: 'send' })}>
// Button content...
</TouchableOpacity>
{tabComponents[this.state.cardstate]}
</View>
);
}
}

Get value from a TextInput component in react native

Dynamically generate a TextInput when you press a button but I can’t get the value that the user digits,try to use states but I can’t because it’s not with the other general textInputs but it’s imported as Field.
try to create a state in the component file and move it to the general view and print it to see if it works and not...is there any way to bring this state?
general view:
import Campo from './campoInput';
constructor(props){
super(props);
this.state={
Cbusto:"",
Ccintura:"",
Ccadera:"",
valueArray: []
};
this.addNewEle = false;
}
agregarCampo=()=>{
this.addNewEle = true;
const newlyAddedValue = { text: 'prueba'};
this.setState({
valueArray: [...this.state.valueArray, newlyAddedValue]
});
}
render(){
return(
------Here are the normal textInput-----
<View style={{ flex: 1, padding: 4 }}>
{this.state.valueArray.map((ele) => {
return <Campo item={ele} />;
})}
</View>
<View style={styles.flex}>
<View style={styles.ButtonAdd}>
<Button
title="Add input"
color="#B13682"
onPress={this.agregarCampo}
></Button>
</View>
)
}
Component:
constructor(props){
super(props);
this.state={
info:""
};
}
render(){
return(
<View>
<Text>pruba:{this.props.item.text}</Text>
<View style={styles.input}>
<TextInput onChangeText={(text) => this.setState({info:text})}></TextInput>
</View>
</View>
)
}
can be solved by adding the onChangeText event to the Field component in the overview and in the same way in the TextInput of the component being imported, using props status
General view:
<View style={{ flex: 1, padding: 4 }}>
{this.state.valueArray.map((ele) => {
return <Campo item={ele}
onChangeText={(text) => this.setState({ info: text })}
/>;
})}
</View>
Component
<View>
<Text>pruba:{this.props.item.text}</Text>
<View style={styles.input}>
<TextInput onChangeText={this.props.onChangeText}></TextInput>
</View>
</View>

Custom Radio Button React Native

Hey there so i'm new to react native and javascript and currently i'm learning to make a custom radio button with images it looks like this my custom radio button in this page user is going to pick one button from the list, and i want to make it when the page first render it will show one pressed button and user is only allowed to pick one button. Can anyone tell me how to figure this out? Thanks in advance
here are my codes
RadioButton.js
export default class RadioButton extends Component {
constructor(props) {
super(props);
this.state = {
selected: this.props.currentSelection === this.props.value,
}
}
button() {
var imgSource = this.state.selected? this.props.normalImg : this.props.selectedImg;
return (
<Image
source={ imgSource }
/>
);
}
render() {
let activeButton = this.props.activeStyle ? this.props.activeStyle : styles.activeButton;
return (
<View style={[styles.container, this.props.containerStyle, this.state.selected || this.props.normalImg ? activeButton : inactiveButton]}>
<TouchableOpacity onPress={() => {
this.setState({ selected: !this.state.selected });
}}>
{
this.button()
}
</TouchableOpacity>
</View>
);
}
}
ActivityLog.js
class ActivityLog extends Component {
constructor(props){
super(props);
}
render() {
return (
<View style={styles.innerContainer}>
<Text style={styles.dialogText}>{`Log my activity at ${time} as...`}</Text>
<View style={styles.buttonContainer}>
<RadioButton selectedImg={img.activity.breakA} normalImg={img.activity.break} containerStyle={{marginHorizontal: normalize(10)}}/>
<RadioButton selectedImg={img.activity.meetingA} normalImg={img.activity.meeting} containerStyle={{marginHorizontal: normalize(10)}}/>
</View>
<View style={styles.buttonContainer}>
<RadioButton selectedImg={img.activity.otwA} normalImg={img.activity.otw} containerStyle={{marginHorizontal: normalize(10)}}/>
<RadioButton selectedImg={img.activity.officeA} normalImg={img.activity.office} containerStyle={{marginHorizontal: normalize(10)}}/>
</View>
);
}
}
Extract the activeStatus to ActivityLog so as to track which button is selected,right now you are maintaing a state for every button as a local state.So it is difficult to know other components to know about the button's active status.
Here is a generic implementation for rough idea.
const Child=(props)=>{
<TouchableOpacity onPress={props.handlePress}>
<Text style={[baseStyle,active && activeStyle]}>{props.title}</Text>
</TouchableOpacity>
}
class Parent extends React.Component{
state={
selectedChild:''
}
changeSelection=(sometitle)=>{
this.setState({
selectedChild:sometitle
})
}
render(){
return(
<View>
<Child handlePress={()=>this.changeSelection('1')} active={this.state.selectedChild==='1'}/>
<Child handlePress={()=>this.changeSelection('2')} active={this.state.selectedChild==='2'}/>
<Child handlePress={()=>this.changeSelection('3')} active={this.state.selectedChild==='3'}/>
<Child handlePress={()=>this.changeSelection('4')} active={this.state.selectedChild==='4'}/>
</View>
)
}
}
Expo demo Link

React-Native: Access TextField value in another class

As an iOS dev I'm struggling a bit with react native.
I have two components inside different classes:
Component A is a view with a TextInput
class A extends Component<Props>{
state = {
textFieldValue: ""
};
render() {
return (
<View>
<TextInput placeholder={this.props.placeholderText}
ref={textField => {
this.textField = textField;
}}
value={this.state.textFieldValue}
onChange={e => this.setState({ textFieldValue: e.target.value})}/>
</View>
);}
}
Component B uses A in it's view
class B extends Component<Props>{
render() {
return (
<View>
<A placeholder={"test"}/>
<TouchableOpacity onPress={() => {
//show text of input A here
}}>
<View>
<Text>{text}</Text>
</View>
</TouchableOpacity>
</View>
);}
}
How can I access the value/state with the value of the TextInput in A from B to show it on the button press?
Try this on Class B
class B extends Component<Props>{
render() {
return (
<View>
<A placeholder={"test"} ref={c => this.textRef = c}/>
<TouchableOpacity onPress={() => {
//show text of input A here
alert(this.textRef.state.textFieldValue)
}}>
<View>
<Text>{text}</Text>
</View>
</TouchableOpacity>
</View>
);}
}
Access reference of class A through ref props, then get its own state.

onPress change fragment view

I am using react-native and i have a NavigationDrawer.When i press ListItem i change the page. What i want to do now is to change only half of page's view depending on what user presses.
export default class Some extends Component {
render() {
return (
<View style={styles.View1}>
<View style={styles.hed}>
<View style={styles.imageview}>
<Image style={styles.img} source={require('../images/logo3.png')} />
</View>
</View>
<View style={styles.View2}>
<Page2/>
</View>
</View>
);
}
}
So what i want is depending onPress change to Page 3, Page4.. BUT the first view to stay constant.
You can switch the pages with a logic like this:
export default class Some extends Component {
constructor() {
// You define the first page seen
this.state = { currentPage: 1 };
}
onPress = () => {
// Here your logic to choose the page with:
this.setState({ currentPage: ... });
}
render() {
// All of your pages
const pages = {
1: <Page1 />,
2: <Page2 />,
3: <Page3 />,
};
const { currentPage } = this.state;
return (
<View style={styles.View1}>
<View style={styles.hed}>
<View style={styles.imageview}>
<Image style={styles.img} source={require('../images/logo3.png')} />
</View>
</View>
<View style={styles.View2}>
{/* Display the selected page */}
{pages[currentPage]}
</View>
</View>
);
}
}

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