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Question

I have a component and use of this component I can't write the correct input so that you can enter only numbers without, . and so on, please help component use of component

my component

export default function AppTextInput({icon, placeholder,onChangeText, ...otherProps}) {

 const  onChanged =(text) =>{
     let newText = '';
     let numbers = '0123456789';
     for (var i=0; i < text.length; i++) {

             if (numbers.indexOf(text[i]) > -1) {
                 newText = newText + text[i];
             } else {
                 alert("please enter integer numbers only");

             }
     }

   }

   return (

       <View style={styles.container}>
           {icon &&
               <MaterialCommunityIcons style={{marginRight: 10}} name={icon} color={colors.grayMedium} size={20}/>}
           <TextInput style={defaultStyles.text} placeholder={placeholder}
                      onChangeText={(text)=> onChanged(text)}  maxLength={3} {...otherProps}
           ></TextInput>
       </View>
   )
}

use of component

  <View style={{top: -80}}>
                    <AppTextInput icon="timer-sand"  placeholder={"Prep Time"} keyboardType='numeric' onChangeText={(text) => setPrepTime(text)}/>
                    <AppTextInput icon="timer" placeholder={"Round Duration"} keyboardType='number-pad' onChangeText={(text) => setRoundDuration(text)}/>
                    <AppTextInput icon="timer" placeholder={"Break Duration"} keyboardType='number-pad' onChangeText={(text) => setBreakDuration(text)}/>
                    <AppTextInput icon="repeat" placeholder={"Number of Rounds"} keyboardType='number-pad'  onChangeText={(text) => setNumRounds(text)}/>
                    <AppTextInput icon="format-list-numbered" placeholder={"Number of Sets"} keyboardType='number-pad' onChangeText={(text) => setNumSets(text)}/>
                    {exerciseInputEles}
                </View>    

I try this solutions, but it didnt work, i think i don't understand in what place put and how to use, that it start works.

Answer 1

First of all, an argument for the onChange event handler is not a new value of the input but an event object. You can access the value by doing something like this:

onChange(event) {
    let text = event.target.value;
    ...

Answer 2

i try do like that but

export default function AppTextInput({icon, placeholder,onChangeText, ...otherProps}) {

  const  onChanged =(text) =>{
      let newText = '';
      let numbers = '0123456789';
      for (var i=0; i < text.length; i++) {

              if (numbers.indexOf(text[i]) > -1) {
                  newText = newText + text[i];
              } else {
                  alert("please enter integer numbers only");

              }
      }

    }

    return (

        <View style={styles.container}>
            {icon &&
                <MaterialCommunityIcons style={{marginRight: 10}} name={icon} color={colors.grayMedium} size={20}/>}
            <TextInput style={defaultStyles.text} placeholder={placeholder}
                       onChangeText={(text)=> onChanged(text)}  maxLength={3} {...otherProps}
            ></TextInput>
        </View>
    )
}

when i input alert work, but onChangeText={(text) => setNumRounds(text)} and other don't see my input, why?

  <View style={{top: -80}}>
                    <AppTextInput icon="timer-sand"  placeholder={"Prep Time"} keyboardType='numeric' onChangeText={(text) => setPrepTime(text)}/>
                    <AppTextInput icon="timer" placeholder={"Round Duration"} keyboardType='number-pad' onChangeText={(text) => setRoundDuration(text)}/>
                    <AppTextInput icon="timer" placeholder={"Break Duration"} keyboardType='number-pad' onChangeText={(text) => setBreakDuration(text)}/>
                    <AppTextInput icon="repeat" placeholder={"Number of Rounds"} keyboardType='number-pad'  onChangeText={(text) => setNumRounds(text)}/>
                    <AppTextInput icon="format-list-numbered" placeholder={"Number of Sets"} keyboardType='number-pad' onChangeText={(text) => setNumSets(text)}/>
                    {exerciseInputEles}
                </View>

Answer 3

Here is the code you can use:

1. I move the onChanged function you have to the other file and use Regex to replace the non-digit character with empty string.

Aside from that I changed the input value of your onChangeText from (text)=> onChanged(text) to onChangeText (it's the props), because onChanged is not there anymore.

export default function AppTextInput({
  icon,
  placeholder,
  onChangeText,
  ...otherProps
}) {
  return (
    <View style={styles.container}>
      {icon && (
        <MaterialCommunityIcons
          style={{ marginRight: 10 }}
          name={icon}
          color={colors.grayMedium}
          size={20}
        />
      )}
      <TextInput
        style={defaultStyles.text}
        placeholder={placeholder}
        onChangeText={onChangeText}
        maxLength={3}
        {...otherProps}
      ></TextInput>
    </View>
  );
}

2. Here I added the function called replaceNonNumeric , the function is used to replace any non-numeric digit to an empty string, so there will be only digit in it.

3. I called replaceNonNumeric right before you change the state and passed the new value to the setState .

...
 const replaceNonNumeric = (text) => {
    return text.replace(/[^0-9]/g, '');
  };

  return (
    <View style={{ top: -80 }}>
      <AppTextInput
        icon="timer-sand"
        placeholder={'Prep Time'}
        keyboardType="numeric"
        onChangeText={(text) => {
          const newText = replaceNonNumeric(text);
          setPrepTime(newText);
        }}
      />
      <AppTextInput
        icon="timer"
        placeholder={'Round Duration'}
        keyboardType="number-pad"
        onChangeText={(text) => {
          const newText = replaceNonNumeric(text);
          setRoundDuration(newText);
        }}
      />
      <AppTextInput
        icon="timer"
        placeholder={'Break Duration'}
        keyboardType="number-pad"
        onChangeText={(text) => {
          const newText = replaceNonNumeric(text);
          setBreakDuration(newText);
        }}
      />
      <AppTextInput
        icon="repeat"
        placeholder={'Number of Rounds'}
        keyboardType="number-pad"
        onChangeText={(text) => {
          const newText = replaceNonNumeric(text);
          setNumRounds(newText);
        }}
      />
      <AppTextInput
        icon="format-list-numbered"
        placeholder={'Number of Sets'}
        keyboardType="number-pad"
        onChangeText={(text) => {
          const newText = replaceNonNumeric(text);
          setNumSets(text);
        }}
      />
      {exerciseInputEles}
    </View>
...