Develop Reference

Remove uploaded documents from list

I currently have a document uploader and when a document is uploaded and save is clicked it will render a saved documents summary panel. Basically what I'm wanting to do is onclick of the DeleteIconSmall I want to remove the document name from the summary.
const SavedDocument = ({ document }: { document: DocumentUploaderFile }) => {
return (
<SavedDocumentWrapper>
<StepCompleteIconSmall />
<SavedDocumentName>{document.name}</SavedDocumentName>
<DeleteIconSmall />
</SavedDocumentWrapper>
)
}

If you're looking for a general approach, I'd provide an onDelete prop to SavedDocument handle removal in the parent. If you just want to clear document.name based on whether that icon's been clicked - all inside this component - you'll want to add a click handler to the icon and store state that tracks whether the icon's been clicked, then choose not to render the name if that state variable is true.
Assuming there is an onClick prop on your delete icon (if there's not you may need to wrap the icon with something that does handle clicks), something like this might work:
const SavedDocument = ({ document }: { document: DocumentUploaderFile }) => {
const [hasDeletedDocument, setHasDeletedDocument] = useState(false);
return (
<SavedDocumentWrapper>
<StepCompleteIconSmall />
<SavedDocumentName>{hasDeletedDocument ? '' : document.name}</SavedDocumentName>
<DeleteIconSmall onClick={() => setHasDeletedDocument(false)} disabled={hasDeletedDocument} />
</SavedDocumentWrapper>
)
}

I want the input data to go into the title and the textarea data to go into the content

import React from 'react';
export default class CreateNote extend React.component {
constructor(props) {
super(props);
this.state = {note:{title:" ",content:" "} };
console.log(this.state);
}
const inputEvent = (event) => {
const value = event.target.value;
const name = event.target.name;
this.setState({
note:{title: ,content: }
})
}
render(){
return(
<input
type="text"
placeholder="Title"
name="title"
id=""
value={note.title}
onChange={inputEvent}
/>
<textarea
name="contant"
id=""
value={note.contant}
cols=""
rows=""
placeholder="Write a Notes"
onChange={inputEvent}
onClick={expanded}>
</textarea>
)
}
When I write text in the input field and textarea then do not go data to note state. I want the input data to go into the title and the textarea data to go into the content.
Now I will write what on setState? I want to see result in the console.

Tip: Your code is riddled with errors and typos (e.g., CreateNote extend React.component instead of CreateNote extends React.Component , writing const for a function inside a Class Component, contant instead of content). For better chances of getting a help, kindly post the working code that you have, so that duplicating the issue becomes easier for the people looking to help you.
Now on to the solution. If you are a beginner, the best way to get what you want is to make separate functions - one that is triggered when the text inside the input is changed, and the other which is triggered when the text inside textarea is changed.
Note that you have kept title and content inside a state object note. This means in order to change title or content, you have to update the entire note object. Be careful if you update just one key of note without persisting the other one (e.g., if you update title only and want to leave content unaffected), you should use the spread operator ... which helps to clone the object's values, so then after that you can update the value of the key you want.
titleChange = (e) => {
this.setState({
note: {
...this.state.note,
title: e.target.value
}
});
};
contentChange = (e) => {
this.setState({
note: {
...this.state.note,
content: e.target.value
}
});
};
Update, a cleaner approach: We can also use the "name" attribute of the input and textarea to our benefit and combine the two functions into one (I've named it inputChange )
inputChange = (e) => {
this.setState({
note: {
...this.state.note,
[e.target.name]: e.target.value
}
});
};
You can find a working CodeSandBox here. Note that using spread operator will not be necessary if you move out the required fields title and content out from notes and make them state variables directly. Check out the AppWithoutNote.js file to see how it can be implemented.

Dynamically adding input fields and keeping track of what was entered

I am wanting to dynamically create input field values for each category a user creates, the issue is how can I keep track of what the user enters into the input field. As I cannot create X amount of states as it is dynamic. Any tips would be much appreciated, my code is shown below:
var categories = newData.map((category,index) => {
console.log(category)
return (
<div className="content row marginCenter" key={category._id}>
<p>{category.category}</p>
<input type="text" /> //How do I keep track of what was entered for this input field??
<button onClick={() => this.addCategoryLink(category._id)}>Add
link</button>
</div>
)
})

I am wondering how to bind that to the button element
The React docs have a section related to the core of this question:
https://reactjs.org/docs/handling-events.html#passing-arguments-to-event-handlers
Assuming your state holds an array of "categories" objects- essentially, I think what you're looking for boils down to something like this in your map function:
{this.state.categories.map(category => (
<input
type="text"
onChange={event => this.handleCategoryChange(category, event)}
value={category.value}
/>
)}
And then a change handler that looks something like this:
handleCategoryChange = (category, event) => {
const value = event.currentTarget.value;
this.setState(state => {
// Create a copy of the categories array:
const categories = [...state.categories];
// Create a copy of the category, with an updated value:
categories[category.index] = {
...category,
value
};
// Update state with the new values:
return { categories };
});
};
Here's a simple demo:
https://codesandbox.io/s/woqpwvl777

i have other Way for doing this , Of course this way just working well in some situation , forExample when you have just 1 or 3 value
i think you wanna create Input , and there Input are dynamic , and you want define that , if user click in first Button , you get and use first TextInput (value)
in my way ( again i say this : this way just well in some situation ) , we Create data Json like this
[
{ id: n ,
category: 'some',
value: ''
}
in this structure Value key , in the mounting contain nothing or null value if the Value not defined before
for now i create one handler method and this method, called after onChange Event fired on
<input onChange={(e) => this.getValue(category.id,e)} />
that element , this means when user start fill input onChange event handle function and update your state
getValue(id,e) {
let thisId = id-1;
let vs = this.state.c;
vs[thisId].value = e.target.value;
this.setState({
c:vs
});
let v = this.state.c[thisId];
console.log(v);
}
i create Pen in this address -> https://codepen.io/hamidrezanikoonia/pen/vRyJRx?editors=1111
you can check console , for more details ( open console tab in codepen )
and for more details , i create two method , the first fired when input (text) filled ( onChange event ) , and the other fired when clicked on button ( click event )

how to add css classes to a component in react?

So basically what I am doing is iterating through an array of data and making some kind of list. What I want to achieve here is on clicking on a particular list item a css class should get attached.
Iteration to make a list
var sports = allSports.sportList.map((sport) => {
return (
<SportItem icon= {sport.colorIcon} text = {sport.name} onClick={this.handleClick()} key= {sport.id}/>
)
})
A single list item
<div className="display-type icon-pad ">
<div className="icons link">
<img className="sport-icon" src={icon}/>
</div>
<p className="text-center">{text}</p>
</div>
I am not able to figure out what to do with handleClick so that If I click on a particular list it gets highlighted.

If you want to highlight the particular list item it's way better to call the handleClick function on the list item itself, and you can add CSS classes more accurately with this approach,
here is my sample code to implement the single list component
var SingleListItem = React.createClass({
getInitialState: function() {
return {
isClicked: false
};
},
handleClick: function() {
this.setState({
isClicked: true
})
},
render: function() {
var isClicked = this.state.isClicked;
var style = {
'background-color': ''
};
if (isClicked) {
style = {
'background-color': '#D3D3D3'
};
}
return (
<li onClick={this.handleClick} style={style}>{this.props.text}</li>
);
}
});

Keep a separate state variable for every item that can be selected and use classnames library to conditionally manipulate classes as facebook recommends.
Edit: ok, you've mentioned that only 1 element can be selected at a time,it means that we only need to store which one of them was selected (I'm going to use the selected item's id). And also I've noticed a typo in your code, you need to link the function when you declare a component, not call it
<SportItem onClick={this.handleClick} ...
(notice how handleClick no longer contains ()).
And now we're going to pass the element's id along with the event to the handleClick handler using partial application - bind method:
<SportItem onClick={this.handleClick.bind(this,sport.id} ...
And as I said we want to store the selected item's id in the state, so the handleClick could look like:
handleClick(id,event){
this.setState({selectedItemId: id})
...
}
Now we need to pass the selectedItemId to SportItem instances so they're aware of the current selection: <SportItem selectedItemId={selectedItemId} ....Also, don't forget to attach the onClick={this.handleClick} callback to where it needs to be, invoking which is going to trigger the change of the state in the parent:
<div onClick={this.props.onClick} className={classNames('foo', { myClass: this.props.selectedItemId == this.props.key}); // => the div will always have 'foo' class but 'myClass' will be added only if this is the element that's currently selected}>
</div>

React - change input defaultValue by passing props

Consider this example:
var Field = React.createClass({
render: function () {
// never renders new value...
return (
<div>
<input type="text" defaultValue={this.props.value || ''} />
</div>
);
}
});
var App = React.createClass({
getInitialState: function () {
return {value: 'Hello!'};
},
changeTo: function (str) {
this.setState({value: str});
},
render: function () {
return (
<div>
<Field value={this.state.value} />
<button onClick={this.changeTo.bind(null, 'Whyyyy?')}>Change to "Whyyyy?"</button>
<button onClick={this.changeTo.bind(null, void 0)}>Change to undefined</button>
</div>
);
}
});
React.render(
<App />,
document.getElementById('app')
);
I want to pass value into defaultValue as prop of dumb input component. However it never re-renders it.

As a previous answer mentioned, defaultValue only gets set on initial load for a form. After that, it won't get "naturally" updated because the intent was only to set an initial default value.
You can get around this if you need to by passing a key to the wrapper component, like on your Field or App component, though in more practical circumstances, it would probably be a form component. A good key would be a unique value for the resource being passed to the form - like the id stored in the database, for example.
In your simplified case, you could do this in your Field render:
<div key={this.props.value}>
<input type="text" defaultValue={this.props.value || ''} />
</div>
In a more complex form case, something like this might get what you want if for example, your onSubmit action submitted to an API but stayed on the same page:
const Form = ({item, onSubmit}) => {
return (
<form onSubmit={onSubmit} key={item.id}>
<label>
First Name
<input type="text" name="firstName" defaultValue={item.firstName} />
</label>
<label>
Last Name
<input type="text" name="lastName" defaultValue={item.lastName} />
</label>
<button>Submit!</button>
</form>
)
}
Form.defaultProps = {
item: {}
}
Form.propTypes = {
item: PropTypes.object,
onSubmit: PropTypes.func.isRequired
}
When using uncontrolled form inputs, we generally don't care about the values until after they are submitted, so that's why it's more ideal to only force a re-render when you really want to update the defaultValues (after submit, not on every change of the individual input).
If you're also editing the same form and fear the API response could come back with different values, you could provide a combined key of something like id plus timestamp.

defaultValue only works for the initial load. After that, it won't get updated. You need to maintain the state for you Field component:
var Field = React.createClass({
//transfer props to state on load
getInitialState: function () {
return {value: this.props.value};
},
//if the parent component updates the prop, force re-render
componentWillReceiveProps: function(nextProps) {
this.setState({value: nextProps.value});
},
//re-render when input changes
_handleChange: function (e){
this.setState({value: e.target.value});
},
render: function () {
// render based on state
return (
<div>
<input type="text" onChange={this._handleChange}
value={this.state.value || ''} />
</div>
);
}
});

I'm fairly certain this has to do with Controlled vs. Uncontrolled inputs.
If I understand correctly, since your <input> is Uncontrolled (doesn't define a value attribute), then the value will always resolve to the value that it is initialized with. In this case Hello!.
In order to overcome this issue, you can add a value attribute and set it during the onChange:
var Field = React.createClass({
render: function () {
// never renders new value...
return (
<div>
<input type="text" defaultValue={this.props.default || ''} value={this.props.value} />
</div>
);
}
});
Here is a plunker showing the change.

You can make the input conditionally and then every time you want to force an update of the defaultValue you just need to unmount the input and then immediately render it again.

The issue is here:
onClick={this.changeTo.bind(null, 'Whyyyy?')}
I'm curious why you bind to null.
You want to bind to 'this', so that changeTo will setState in THIS object.
Try this
<button onClick={this.changeTo.bind(this, 'Whyyyy?')}>Change to "Whyyyy?"</button>
<button onClick={this.changeTo.bind(this, void 0)}>Change to undefined</button>
In Javascript, when a function is called, its called in the scope where it was called from, not where it was written (I know, seems counter intuitive). To ensure it is called in the context you write it, you need to '.bind(this)'.
To learn more about binding and function scope, there are lots of online tutes, (some much better than others) - you might like this one: http://ryanmorr.com/understanding-scope-and-context-in-javascript/
I also recommend using the React Dev tools if you are using firefox or chrome, this way you would have been able to see that state.message was not changing:
https://facebook.github.io/react/blog/2015/09/02/new-react-developer-tools.html

Use conditional rendering, then the component will load correct initial value. Something like in this module:
class MenuHeaderInput extends React.Component{
constructor(props){
super(props);
this.handleBlur = this.handleBlur.bind (this);
}
handleBlur (e) {
this.props.menuHeaderUpdate(e.target.value);
}
render(){
if (this.props.menuHeader) {
return (
<div className="w3-row w3-margin" onClick = {() => this.props.handleTitleClick (10)}>
<div className="w3-third" ><pre></pre></div>
<input
className = {"w3-third w3-input w3-jumbo " + EDIT_COLOR}
type = "text"
defaultValue = {this.props.menuHeader}
onBlur = {this.handleBlur}
/>
<div className="w3-third" ><pre></pre></div>
</div>
)
}
else {
return null;
}
}
}

Related to Sia's excellent answer above: https://stackoverflow.com/a/41962233/4142459.
For my case I had a few ways in which a form could be updated:
users could input values into form fields
An API request allowed users to restore from previous versions
Users could navigate to a filled out form (using queryParams of the URL)
clearing the form fields.
Etc more ways of allowing all the fields or just a single change to happen from user action or websockets.
I found that the easiest way to make sure the state of the form is reflected in its inputs is indeed:
To provide a manually-controlled key prop on the top level of the form or parent element to the form (as long as it is above the inputs in the DOM tree.
When users are typing a key update does not need to happen.
I made the key be a simple formHistoricalVersion and as certain updates external to a user typing/selecting/etc interacting with the form field's values happened I incremented the formHistoricalVersion.
This made sure that the state of the form whether by user action or by API request was in-sync--I had complete control over it.
Other solutions I tried:
While making the API request make the whole form disappear (when loading change to a loading spinner instead of the form). Disadvantage to performance and for clearForm it was a bit crazy to do, but possible with setImmediate to convert the form to a loading spinner when they first clear it, then setting isLoading back to false in the setImmediate.
Adding a key on each input: this worked amazingly, but it had a weird blip whenever users would type so I had to get rid of it.
Putting a static key for the form (field.id) (as suggested by above answer) didn't cover all the use cases I had.
In conclusion, it worked pretty easily to set the key of the form with react/redux, I just would add the equivalent of:
return {
...state,
formFieldState: payload.formFields,
historicalFormVersion: state.historicalFormVersion + 1
}
This was necessary because I was using some 3rd party libraries and my own Numeric Input that took in value as a prop but used value as a defaultValue:
const NumberDisplay: FunctionComponent = ({ value, setValue }) => (
<input
defaultValue={convertToSpecialNumberDisplay(value)}
onBlur={(e) => convertToSpecialNumberDisplay(e.target.value)}
onFocus={(e) => convertToNumberFromDisplay(e.target.value)}
onChange={(e) => setValue(e.target.value)}
/>
)
Approximate Redux of overall Form:
const FullForm: FunctionComponent = () => {
const dispatch = useDispatch();
const formState = useState((state) => state.formState);
const formHistoricalVersion = useState((state) => state.formHistoricalVersion);
return (
<form key={formHistoricalVersion}>
{renderFormFields(formState, dispatch)}
</form>
)
}

I also face this problem, what I did was to manually update the input value when the props has change. Add this to your Field react class:
componentWillReceiveProps(nextProps){
if(nextProps.value != this.props.value) {
document.getElementById(<element_id>).value = nextProps.value
}
}
You just need to add an id attribute to your element so that it can be located.