Only numbers. Input number in React
JavascriptRegexReactjsJavascript Problem Overview
I'm trying to exclude minus and plus from input, but it's going wrong:
handleChange(event) {
const value = event.target.value.replace(/\+|-/ig, '');
this.setState({financialGoal: value});
}
Render input code:
<input style={{width: '150px'}} type="number" value={this.state.financialGoal} onChange={this.handleChange}/>
Javascript Solutions
Solution 1 - Javascript
Simply way in React
<input
onKeyPress={(event) => {
if (!/[0-9]/.test(event.key)) {
event.preventDefault();
}
}}
/>
Solution 2 - Javascript
I tried to mimic your code and noticed that there's an issue on React with <input type='number' />
. For workaround, check this example and try it yourself: https://codepen.io/zvona/pen/WjpKJX?editors=0010
You need to define it as normal input (type='text') with pattern for numbers only:
<input type="text" pattern="[0-9]*"
onInput={this.handleChange.bind(this)} value={this.state.financialGoal} />
And then to compare the validity of input:
const financialGoal = (evt.target.validity.valid) ?
evt.target.value : this.state.financialGoal;
The biggest caveat on this approach is when it comes to mobile --> where keyboard isn't in numeric but in normal alphabetic format.
Solution 3 - Javascript
one line of code
<input value={this.state.financialGoal} onChange={event => this.setState({financialGoal: event.target.value.replace(/\D/,'')})}/>
Solution 4 - Javascript
If you want to maintain input type='number'
(probably for mobile devices to trigger the numeric keyboard) you should use onInput
instead of onChange
to capture your event changes.
Using onInput
fixed a bug where typing text into a number input would bypass the validation I had assigned to it in onChange
. Once I fixed this function to be called in onInput
it triggered in all instances.
Here's an example of what I'm doing:
<input
type='number'
id={`player${index}Score`}
className='form-control'
pattern='[0-9]{0,5}'
onInput={(event) => this.enterScore(event, index)}
value={this.props.scoreLabel(this.state.scores[index])}
/>
I hope this helps!
EDIT - 08-03-2018:
I came up with a better solution. Use type='tel' along with a pattern regex within the input component itself.
The nuts and bolts of how I wired this up is here:
class Input extends React.Component {
state = {message: '3'};
updateNumber = (e) => {
const val = e.target.value;
// If the current value passes the validity test then apply that to state
if (e.target.validity.valid) this.setState({message: e.target.value});
// If the current val is just the negation sign, or it's been provided an empty string,
// then apply that value to state - we still have to validate this input before processing
// it to some other component or data structure, but it frees up our input the way a user
// would expect to interact with this component
else if (val === '' || val === '-') this.setState({message: val});
}
render() {
return (
<input
type='tel'
value={this.state.message}
onChange={this.updateNumber}
pattern="^-?[0-9]\d*\.?\d*$"
/>
);
}
}
ReactDOM.render(<Input />, document.getElementById('main'));
I have an example of this working on Codepen here
Solution 5 - Javascript
-
To stop typing, use
onKeyPress
notonChange
. -
Using
event.preventDefault()
insideonKeyPress
means STOP the pressing event . -
Since
keyPress
handler is triggered beforeonChange
, you have to check the pressed key (event.keyCode
), NOT the current value of input (event.target.value
)onKeyPress(event) { const keyCode = event.keyCode || event.which; const keyValue = String.fromCharCode(keyCode); if (/\+|-/.test(keyValue)) event.preventDefault(); }
Demo below
const {Component} = React;
class Input extends Component {
onKeyPress(event) {
const keyCode = event.keyCode || event.which;
const keyValue = String.fromCharCode(keyCode);
if (/\+|-/.test(keyValue))
event.preventDefault();
}
render() {
return (
<input style={{width: '150px'}} type="number" onKeyPress={this.onKeyPress.bind(this)} />
)
}
}
ReactDOM.render(<Input /> , document.querySelector('#app'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<section id="app"></section>
Solution 6 - Javascript
Solution
Today I find use parseInt()
is also a good and clean practice. A onChange(e)
example is below.
Code
onChange(e){
this.setState({[e.target.id]: parseInt(e.target.value) ? parseInt(e.target.value) : ''})
}
Explanation
parseInt()
would returnNaN
if the parameter is not a number.parseInt('12a')
would return 12.
Solution 7 - Javascript
I am using isNaN function of JS to verify whether it is number or not.
const handleChange2 = (e) => {
if (isNaN(e.target.value)) {
return;
}
const onlyNums = e.target.value.replace(/[^0-9]/g, "");
setFormData({
...formData,
[e.target.name]: onlyNums,
});
};
const [formData, setFormData] = useState({
name: "",
phone: "",
email: "",
address: "",
});
<input
value={phone}
onChange={(e) => handleChange2(e)}
placeholder="Phone"
type="text"
name="phone"
required
/>
Note:The value stored in the state will string, if you want it to be a number/int just use Number to convert it into integer. ex: let phone= Number(formData.phone)
Solution 8 - Javascript
The most effective and simple solution I found:
<input
type="number"
name="phone"
placeholder="Phone number"
onKeyDown={e => /[\+\-\.\,]$/.test(e.key) && e.preventDefault()}
/>
Solution 9 - Javascript
<input
className="input-Flied2"
type="TEXT"
name="userMobileNo"
placeholder="Moble No"
value={phonNumber}
maxLength="10"
onChange={handleChangeInput}
required
/>
const handleChangeInput = (e) => {
const re = /^[0-9\b]+$/; //rules
if (e.target.value === "" || re.test(e.target.value)) {
setPhoneNumber(e.target.value);
}
};
Solution 10 - Javascript
Here is a solution with onBlur, it can be very helpful as it also allows you to format the number the way you need it without requiring any black magic or external library.
2020 React Hooks
const toNumber = (value: string | number) => {
if (typeof value === 'number') return value
return parseInt(value.replace(/[^\d]+/g, ''))
}
const formatPrice = (price: string | number) => {
return new Intl.NumberFormat('es-PY').format(toNumber(price))
}
<input
defaultValue={formatPrice(price)}
onBlur={e => {
const numberValue = toNumber(e.target.value)
setPrice(numberValue)
e.target.value = formatPrice(numberValue)
}}
type='tel'
required
/>
How it works:
- Set initial value via
defaultValue
- Allow user to freely type anything they feel
- onBlur (once the input looses focus):
- replace any character that is not a digit with an empty string
- setState() or dispatch() to manage state
- set the value of the input field to the numeric value and apply optional formatting
Pay attention: In case your value come from a async source (e.g. fetch): Since defaultValue will only set the value on the first render, you need to make sure to render the component only once the data is there.
Solution 11 - Javascript
The fastest way I found was adding a onKeyPress like this:
<input
type="text"
name="example"
value="Type here"
onKeyPress={(event) => {
if (!/[0-9]/.test(event.key)) {
event.preventDefault();
}
}}
>
Solution 12 - Javascript
2019 Answer Late, but hope it helps somebody
> This will make sure you won't get null on an empty textfield
- Textfield value is always 0
- When backspacing, you will end with 0
- When value is 0 and you start typing, 0 will be replaced with the actual number
// This will make sure that value never is null when textfield is empty
const minimum = 0;
export default (props) => {
const [count, changeCount] = useState(minimum);
function validate(count) {
return parseInt(count) | minimum
}
function handleChangeCount(count) {
changeCount(validate(count))
}
return (
<Form>
<FormGroup>
<TextInput
type="text"
value={validate(count)}
onChange={handleChangeCount}
/>
</FormGroup>
<ActionGroup>
<Button type="submit">submit form</Button>
</ActionGroup>
</Form>
);
};
Solution 13 - Javascript
Here's my solution of plain Javascript
Attach a keyup
event to the input
field of your choice - id
in this example.
In the event-handler function just test the key of event.key
with the given regex.
In this case if it doesn't match we prevent the default action of the element - so a "wrong" key-press within the input box won't be registered thus it will never appear in the input box.
let idField = document.getElementById('id');
idField.addEventListener('keypress', function(event) {
if (! /([0-9])/g.test(event.key)) {
event.preventDefault();
}
});
The benefit of this solution may be its flexible nature and by changing and/or logically chaining regular expression(s) can fit many requirements.
E.g. the regex /([a-z0-9-_])/g
should match only lowercase English alphanumeric characters with no spaces and only -
and _
allowed.
> Note: that if you use /[a-z]/gi
(note the i at the end) will ignore
> letter case and will still accept capital letters.
Solution 14 - Javascript
We can use the Terinary operator and do like this. Also using useState to set the values to the object
<input id="cost" name="cost" type="text" onChange = {e=>isNaN(e.target.value)?e.target.value="":setItem({...item,cost:parseInt(e.target.value)})} />
Solution 15 - Javascript
Use a pattern validation in order to allow one point (for decimals) and not allow spaces. You need to pass an arrow function in setState() in order to immediately update the state value, once it will be placed back in the input field.
*considering a class component
Given some context to the state variable.
constructor(props) {
super(props);
this.state = {inputValue: ''};
};
The input field content is evaluated against the pattern
regex. If both match, the event's validity.valid
property is assigned as true
, otherwise false
:
<input
pattern = '[0-9]*\.?[0-9]*'
type = 'text'
value = {this.state.inputValue}
onChange = {this.handleChange}
...>
In handleChange
, the state is immediately updated if validity.valid
is true, otherwise it keeps the previous value (and the text in the input field doesn't change).
handleChange = (e) => {
this.setState((prevState) => (
e.target.validity.valid ? {inputValue: e.target.value} : prevState)
)
};
Solution 16 - Javascript
Define an input with an onChange()
method like below (in my case, childState contains the state, passed down to this child component).
<input
...
value={this.props.childState.volume}
...
onChange={(e) => handleChangeInteger(e, {volume: e.target.value})}
/>
One approach I used was to install validatorJS (npm install validator --save
)
I then defined a function handleChangeInteger
, which takes an object that will be used to change your state, in this case, {volume: e.target.value}
. Note: I needed the OR condition to allow my input to be blank, otherwise it would not let the user backspace (delete) the last integer if they wanted the field blank.
const handleChangeInteger = (e, obj_to_return) => {
if (validator.isInt(e.target.value) || e.target.value == '') {
this.props.childSetState(obj_to_return)
}
}
The user will now not be allowed to type anything other than backspace, 0-9, or e (this is a number..) in the input field.
I referenced this post to create my solution: https://stackoverflow.com/a/45676912/6169225
Solution 17 - Javascript
After reading all the answers but none really working for numbers only with copy and paste I came up with this solution.
parseInt
solution: fails asparseInt("2a")
is valid;onKeyup sulution:
fails on copy and paste, backspace;- key.which solution: will probably fail on copy and paste;
- type="number" solution: fails on long numbers as
javascript
converts 40817810000000023511 into 40817810000000023500 because it is 53 bit language
<input
name="address.line1"
value={values.address.line1}
onChange={(event: any) => {
if (isFinite(event.target.value)) {
// UPDATE YOUR STATE (i am using formik)
setFieldValue("address.line1", event.target.value);
}
}}
/>
Solution 18 - Javascript
You can try this solution, since onkeypress will be attached directly to the DOM element and will prevent users from entering invalid data to begin with.
So no side-effects on react side.
<input type="text" onKeyPress={onNumberOnlyChange}/>
const onNumberOnlyChange = (event: any) => {
const keyCode = event.keyCode || event.which;
const keyValue = String.fromCharCode(keyCode);
const isValid = new RegExp("[0-9]").test(keyValue);
if (!isValid) {
event.preventDefault();
return;
}
};
Solution 19 - Javascript
handleChange(event) {
const value = event.target.value
let finalValue;
Number.isNaN(parseInt(value)) ? finalValue = 0 : finalValue = parseInt(value)
this.setState({financialGoal: finalValue});
}
Solution 20 - Javascript
Maybe, it will be helpful for someone
Recently I used this solution for my App
I am not sure that is a correct solution but it works fine.
this.state = {
inputValue: "",
isInputNotValid: false
}
handleInputValue = (evt) => {
this.validationField(evt, "isInputNotValid", "inputValue");
}
validationField = (evt, isFieldNotValid, fieldValue ) => {
if (evt.target.value && !isNaN(evt.target.value)) {
this.setState({
[isFieldNotValid]: false,
[fieldValue]: evt.target.value,
});
} else {
this.setState({
[isFieldNotValid]: true,
[fieldValue]: "",
});
}
}
<input className={this.state.isInputNotValid ? "error" : null} type="text" onChange="this.handleInputValue" />
The main idea, that state won't update till the condition isn't true and value will be empty.
Don't need to use onKeyPress, Down etc.,
also if you use these methods they aren't working on touch devices
Solution 21 - Javascript
Set class on your input field:
$(".digitsOnly").on('keypress',function (event) {
var keynum
if(window.event) {// IE8 and earlier
keynum = event.keyCode;
} else if(event.which) { // IE9/Firefox/Chrome/Opera/Safari
keynum = event.which;
} else {
keynum = 0;
}
if(keynum === 8 || keynum === 0 || keynum === 9) {
return;
}
if(keynum < 46 || keynum > 57 || keynum === 47) {
event.preventDefault();
} // prevent all special characters except decimal point
}
Restrict paste and drag-drop on your input field:
$(".digitsOnly").on('paste drop',function (event) {
let temp=''
if(event.type==='drop') {
temp =$("#financialGoal").val()+event.originalEvent.dataTransfer.getData('text');
var regex = new RegExp(/(^100(\.0{1,2})?$)|(^([1-9]([0-9])?|0)(\.[0-9]{1,2})?$)/g); //Allows only digits to be drag and dropped
if (!regex.test(temp)) {
event.preventDefault();
return false;
}
} else if(event.type==='paste') {
temp=$("#financialGoal").val()+event.originalEvent.clipboardData.getData('Text')
var regex = new RegExp(/(^100(\.0{1,2})?$)|(^([1-9]([0-9])?|0)(\.[0-9]{1,2})?$)/g); //Allows only digits to be pasted
if (!regex.test(temp)) {
event.preventDefault();
return false;
}
}
}
Call these events in componentDidMount() to apply the class as soon as the page loads.