Meteor/React, redirect route after changeState - javascript

I have a problem redirecting my routes with react router after a state change.
In fact, my route is working when I'm using a click event who change the state (currentListId), but it's not working when I delete an element by Id (listId), so after a setState( listSelected: "") ...
My routes still display the /idlistselected instead redirect to /.
Here is some code:
Page code:
constructor(props) {
super(props);
this.state = { listSelected: "" };
this.selectList = this.selectList.bind(this);
}
selectList(listId) {
this.setState({ listSelected: listId });
// Here, only the if listId Works
if (listId)
browserHistory.push('/admin/todos/' + listId);
else
browserHistory.push('/admin/todos/');
}
render() {
return (
<ListPanel
listSelected = {this.state.listSelected}
selectList = {this.selectList}
lists = {this.props.lists}
tasks = {this.props.tasks}
/>
Then The ListPanel:
renderLists() {
return this.props.lists.map((list) => (
<List
selectedItemId ={this.props.listSelected}
selectList = {() => this.props.selectList(list._id)}
key = {list._id}
list = {list}
countPendingTasks = {this.countPendingTasks(list._id)}
/>
));
}
And finally the list:
deleteThisList() {
Meteor.call('lists.remove', this.props.list._id, (err) => {
if (!err) {
this.props.selectList(null);
}
});
}
render() {
return (
<ListGroupItem
className={(this.props.list._id == this.props.selectedItemId) ? 'active' : ''}
onClick={this.props.selectList}
>
{this.props.list.name}
<Glyphicon className="pushRight red"onClick={() => this.deleteThisList()}/>
</ListGroupItem>
);
}
If I display the listId in the selectList, I have the past ID when I remove a list .. I can't find why cause I set it to null in the delete function ...
Thanks for the help.

You are overriding the argument to selectList when you are passing it to the List component, thus if you call this.props.selectList in the child component, the original function gets called with the list._id, no matter what arguments you give it.
You can fix this simply by passing the selectedList function down without binding an argument, and then just calling it with the list._id in the List component:
<List
selectList = {this.props.selectList}
...
And in the List component
<ListGroupItem
onClick={() => this.props.selectList(list._id)}
...
Now the null passed in deleteThisList function should get passed properly.

Related

React passing a component as a param to a function

I have a function that takes a Component as its' parameter. The function enables users to render their own popups instead of the ones I provide. However, I'm not able to add some props to said component before adding it to an array.
const addCustomSnack = (Snack, position) => {
let id = generate();
let snackProps = {
key: id,
id,
};
Snack.props = {...Snack.props, ...snackProps}
console.log(Snack);
buildStyle(position);
if (messagesNew.length >= 3) {
que.push(Snack);
addSnacks(messagesNew);
} else {
messagesNew = [...messagesNew, Snack];
addSnacks(messagesNew);
}
console.log(messagesNew);
};
This is what happens
Cannot assign to read only property 'props' of object '#<Object>'
I have tried the following code
const addCustomSnack = (Snack, position) => {
let id = generate();
console.log(Snack);
buildStyle(position);
if (messagesNew.length >= 3) {
que.push(Snack);
addSnacks(messagesNew);
} else {
messagesNew = [...messagesNew, <Snack key={id} id={id} />];
addSnacks(messagesNew);
}
console.log(messagesNew);
};
However, it will result in a React.createElement type error.
Codesandbox
Is there any way for me to add those props into the Snack component successfully?
This is exactly what a react High Order Component does: adding props to the component passed as parameter and return a component back.
If you are getting component in Snack then try below way
return <Snack {...snackProps} />
Using above code this will render any component that is passed to addCustomSnack
You could somehow keep an array of the component to render, each with a ref to the component and and its custom properties, then render it with a map, like so:
// Snack list
constructor(){
this.state = { snacks: [] }
}
// ...
const Lollipop = props => (
<div>
<h1>Lollipop</h1>
<span>Taste: </span> {props.taste}
</div>
)
const ChocolateBar = props => (
<div>
<h1>Chocolate bar</h1>
<span>With fudge: </span> {props.hasFudge ? 'yes': 'no'}
</div>
)
// Push a custom snack in the list
const addCustomSnack = (SnackType, props) => this.state.snacks.push({SnackType, props})
// ...
addSnack(Lollipop, {taste: 'cherry'})
addSnack(Lollipop, {taste: 'cola'})
addSnack(ChocolateBar, {hasFudge: true})
addSnack(ChocolateBar, {})
// render the lsit
const SnackList = () => {
<div>
{ this.state.snacks.map(({SnackType, props}, i) => (
<SnackType {...props} key={i} />
))}
</div>
}
React.cloneElement did exactly what I was looking for. Now, the user can give his own Component, and with cloneElement, I can extend the components props and add it into the array without problems.
const addCustomSnack = (Component, position) => {
let id = generate();
let props = {
removeSnack,
key: id,
id,
index: id
}
let Snack = React.cloneElement(Component, { ...props }, null);
buildStyle(position);
console.log(Snack)
if (messagesNew.length >= 3) {
que.push(Snack);
return addSnacks(messagesNew);
} else {
messagesNew = [...messagesNew, Snack];
return addSnacks(messagesNew);
}
};

ReactJS Wrong Component gets removed from DOM

I have three files: ShopsContainer.js ShopsComponent.js and ShopsItemComponent.js
ShopsContainer maintains an array of shop items in local state that gets passed down into ShopsComponent as props. ShopsComponent then maps through the items array that is being received as props and renders a ShopsItemComponent for each item in the array.
Within my ShopsContainer file, I have a method that removes a shop item from state using the following code:
removeShop = (shopAccount) => {
this.setState(prevState => ({
items: prevState.items.filter(shop => {
return shop.shopAccount !== shopAccount
})
}));
}
When this happens, the correct item is removed from the items array in state, however, whatever the last ShopItem is that is in the DOM at the time of the removeShop call will get removed no matter if it is the correct item that should be removed or not. In other words, when removeShop gets called and the items array in state gets updated correctly, the wrong ShopItemComponent gets removed from the DOM.
What I would like to happen (or what I think should happen) is when removeShop gets called, that shop gets removed from the items array in state and ShopsContainer re-renders causing ShopsComponent to re-render with the updated props being received. And lastly ShopsComponent would map through the newly updated items array in props displaying a `ShopItemComponent for the correct items. Perhaps the problem has to do with the props being updated?
My code is as follows:
ShopsContainer.js
class ShopsContainer extends Component {
constructor() {
this.state = {
items: null
}
this.getAll();
this.removeShop = this.removeShop.bind(this);
}
getAll = () => {
// API request that fetches items and updates state
}
removeShop = (shopAccount) => {
this.setState(prevState => ({
items: prevState.items.filter(shop => {
return shop.shopAccount !== shopAccount
})
}));
}
render() {
return (
<div>
{this.state.items ? <ShopComponent items={this.state.items} removeShop={this.removeShop} /> : <div><h1>Loading...</h1></div>}
</div>
);
}
}
ShopsComponent.js
class ShopsComponent extends Component {
constructor() {
this.handleRemove = this.handleRemove.bind(this);
}
handleRemove = (shopAccount) => {
this.props.removeShop(shopAccount);
}
render() {
return (
<React.Fragment>
<Header />
{this.props.items.map((shopItem, i) => {
return (<ShopItemComponent key={i} item={shopItem} removeShop={this.handleRemove} />);
})}
</React.Fragment>
);
}
}
Your code is working great, but you only has one mistake , your ShopComponent is assign index as a key for each ShopItemComponent and react is tracking those indexes to update the correct component, so you need to set key as a unique value between items, then I realize that shopAccount should be your id for each item.
The solution code is below.
class ShopsComponent extends Component {
handleRemove = (shopAccount) => {
this.props.removeShop(shopAccount);
}
render() {
return (
<React.Fragment>
<Header />
{this.props.items.map((shopItem) => <ShopItemComponent key={shopItem.shopAccount} item={shopItem} removeShop={this.handleRemove} />)}
</React.Fragment>
);
}
}
I hope you can find useful.
Note, when you are using a arrow function into your class, don't bind that method into the constructor, so remove it, because
handleRemove = (shopAccount) => {
this.props.removeShop(shopAccount);
}
is already binded.

Child Component Isn't Updating with New Props

I'm having an issue getting my child component to update with new props. I'm deleting an item from the global state and it's successful. But when the item gets deleted, I'm expecting that item to no longer show. It's still being shown but if I were to move to another screen then back, it's gone. Any idea on what I might be missing here?
Thanks!!
export default class Summary extends Component {
constructor(props) {
super(props);
this.state = {
pickupData: this.props.pickup
};
}
handleDelete(item) {
this.props.deleteLocationItem(item);
}
render() {
const pickup = this.state.pickup;
return (
<View>
{pickup.map((item, i) => (
<LocationItem
name={item}
onPressDelete={() => this.handleDelete(item)}
/>
))}
</View>
);
}
}
const LocationItem = ({ onPressDelete, name }) => (
<TouchableOpacity onPress={onPressDelete}>
<Text>Hi, {name}, CLICK ME TO DELETE</Text>
</TouchableOpacity>
);
------- Additional Info ------
case 'DELETE_LOCATION_INFO':
return Object.assign({}, state, {
pickup: state.pickup.filter(item => item !== action.action)
})
export function deleteLocationInfo(x){
return {
type: DELETE_LOCATION_INFO,
action: x
}
}
Your deleteLocationItem must be something like this:
deleteLocationItem(id) {
this.setState({
items: this.state.items.filter(item => item.id !== id)
});
}
Then inside your Summary class you dont need to set the prop again. Just receive pickup from props like this:
render (
const { pickup } = this.props;
return(
<View>
{ pickup.map
...
Render is happening based on the state which is not updated other than in constructor. When the prop updates from parent, it is not reflected in the state.
Add componentWillReceiveProps method to receive new props and update state, which will cause new data to render
But more preferably, if the state is not being changed in any way after initialization, render directly using the prop itself which will resolve this issue

ReactJS: how to append a component to the App component in React

I am trying to append a "Item" component which consists of some array items, in the main "App" Component. But the component is getting replaced with the new array items instead of getting appended. Following is the code snippet:
//the App render function
render: function() {
return (
<div>
{
this.state.productDisplayed.map(function(product, i) {
return (
<Item source = {product.url} prodId = {product.id} key = {product.id} />
)
})
}
</div>
)
}
//The Item render function
render: function(){
return(
<div className = "col-sm-4" >
<img src = {this.props.source} width = "70%" className = "img-responsive"></img>
<div>{this.props.prodId}
</div>
</div>
)
}
"ProductDisplayed" is an array which gets replaced by new items which are then displayed using a "for" loop.
How can i append the items as if I am adding some extra items to the main App component. I am trying to implement infinite scrolling.
In order to append items to your app component, you need to append data to your productDisplayed state array
For this you can do something like
addItem=(item)=>{
var productDisplayed=[...this.state.productDisplayed];
productDisplayed.push(item);
this.setState({productDisplayed});
}
And you can call this function addItem on some event.
You need to append them to the array in your state. I have used the function argument to setState because your nextState is dependent on your previous state.
component ProductList extends React.Component {
constructor() {
super()
this.setState({
productDisplayed: []
});
}
getMoreItems = ( startingId ) => {
Api.getMoreItems(startingId).then(this.addItems);
}
addItems = ( items ) => {
this.setState(( prevState ) => ({
updatedItems: [...prevState.productDisplayed, ...items]
}));
}
render() {
// no changes
// something triggers this.getMoreItems(id)
}
}

React js onClick can't pass value to method

I want to read the onClick event value properties. But when I click on it, I see something like this on the console:
SyntheticMouseEvent {dispatchConfig: Object, dispatchMarker: ".1.1.0.2.0.0:1", nativeEvent: MouseEvent, type: "click", target
My code is working correctly. When I run I can see {column} but can't get it in the onClick event.
My Code:
var HeaderRows = React.createClass({
handleSort: function(value) {
console.log(value);
},
render: function () {
var that = this;
return(
<tr>
{this.props.defaultColumns.map(function (column) {
return (
<th value={column} onClick={that.handleSort} >{column}</th>
);
})}
{this.props.externalColumns.map(function (column) {
// Multi dimension array - 0 is column name
var externalColumnName = column[0];
return ( <th>{externalColumnName}</th>);
})}
</tr>
);
}
});
How can I pass a value to the onClick event in React js?
Easy Way
Use an arrow function:
return (
<th value={column} onClick={() => this.handleSort(column)}>{column}</th>
);
This will create a new function that calls handleSort with the right params.
Better Way
Extract it into a sub-component.
The problem with using an arrow function in the render call is it will create a new function every time, which ends up causing unneeded re-renders.
If you create a sub-component, you can pass handler and use props as the arguments, which will then re-render only when the props change (because the handler reference now never changes):
Sub-component
class TableHeader extends Component {
handleClick = () => {
this.props.onHeaderClick(this.props.value);
}
render() {
return (
<th onClick={this.handleClick}>
{this.props.column}
</th>
);
}
}
Main component
{this.props.defaultColumns.map((column) => (
<TableHeader
value={column}
onHeaderClick={this.handleSort}
/>
))}
Old Easy Way (ES5)
Use .bind to pass the parameter you want, this way you are binding the function with the Component context :
return (
<th value={column} onClick={this.handleSort.bind(this, column)}>{column}</th>
);
There are nice answers here, and i agree with #Austin Greco (the second option with separate components)
There is another way i like, currying.
What you can do is create a function that accept a parameter (your parameter) and returns another function that accepts another parameter (the click event in this case). then you are free to do with it what ever you want.
ES5:
handleChange(param) { // param is the argument you passed to the function
return function (e) { // e is the event object that returned
};
}
ES6:
handleChange = param => e => {
// param is the argument you passed to the function
// e is the event object that returned
};
And you will use it this way:
<input
type="text"
onChange={this.handleChange(someParam)}
/>
Here is a full example of such usage:
const someArr = ["A", "B", "C", "D"];
class App extends React.Component {
state = {
valueA: "",
valueB: "some initial value",
valueC: "",
valueD: "blah blah"
};
handleChange = param => e => {
const nextValue = e.target.value;
this.setState({ ["value" + param]: nextValue });
};
render() {
return (
<div>
{someArr.map(obj => {
return (
<div>
<label>
{`input ${obj} `}
</label>
<input
type="text"
value={this.state["value" + obj]}
onChange={this.handleChange(obj)}
/>
<br />
<br />
</div>
);
})}
</div>
);
}
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);
<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>
<div id="root"></div>
Note that this approach doesn't solve the creation of a new instance on each render.
I like this approach over the other inline handlers as this one is more concise and readable in my opinion.
Edit:
As suggested in the comments below, you can cache / memoize the result of the function.
Here is a naive implementation:
let memo = {};
const someArr = ["A", "B", "C", "D"];
class App extends React.Component {
state = {
valueA: "",
valueB: "some initial value",
valueC: "",
valueD: "blah blah"
};
handleChange = param => {
const handler = e => {
const nextValue = e.target.value;
this.setState({ ["value" + param]: nextValue });
}
if (!memo[param]) {
memo[param] = e => handler(e)
}
return memo[param]
};
render() {
return (
<div>
{someArr.map(obj => {
return (
<div key={obj}>
<label>
{`input ${obj} `}
</label>
<input
type="text"
value={this.state["value" + obj]}
onChange={this.handleChange(obj)}
/>
<br />
<br />
</div>
);
})}
</div>
);
}
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);
<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>
<div id="root" />
Nowadays, with ES6, I feel we could use an updated answer.
return (
<th value={column} onClick={()=>this.handleSort(column)} >{column}</th>
);
Basically, (for any that don't know) since onClick is expecting a function passed to it, bind works because it creates a copy of a function. Instead we can pass an arrow function expression that simply invokes the function we want, and preserves this. You should never need to bind the render method in React, but if for some reason you're losing this in one of your component methods:
constructor(props) {
super(props);
this.myMethod = this.myMethod.bind(this);
}
[[h/t to #E.Sundin for linking this in a comment]
The top answer (anonymous functions or binding) will work, but it's not the most performant, as it creates a copy of the event handler for every instance generated by the map() function.
This is an explanation of the optimal way to do it from the ESLint-plugin-react:
Lists of Items
A common use case of bind in render is when rendering a list, to have
a separate callback per list item:
const List = props => (
<ul>
{props.items.map(item =>
<li key={item.id} onClick={() => console.log(item.id)}>
...
</li>
)}
</ul>
);
Rather than doing it this way, pull the repeated section into its own
component:
const List = props => (
<ul>
{props.items.map(item =>
<ListItem
key={item.id}
item={item}
onItemClick={props.onItemClick} // assume this is passed down to List
/>
)}
</ul>
);
const ListItem = props => {
const _onClick = () => {
console.log(props.item.id);
}
return (
<li onClick={_onClick}>
...
</li>
);
});
This will speed up rendering, as it avoids the need to create new
functions (through bind calls) on every render.
This is my approach, not sure how bad it is, please comment
In the clickable element
return (
<th value={column} onClick={that.handleSort} data-column={column}> {column}</th>
);
and then
handleSort(e){
this.sortOn(e.currentTarget.getAttribute('data-column'));
}
React Hooks Solution 2022
const arr = [
{ id: 1, txt: 'One' },
{ id: 2, txt: 'Two' },
{ id: 3, txt: 'Three' },
]
const App = () => {
const handleClick = useCallback(
(id) => () => {
console.log("ID: ", id)
},
[],
)
return (
<div>
{arr.map((item) => (
<button onClick={handleClick(item.id)}>{item.txt}</button>
))}
</div>
)
}
You can pass a function to useCallback's return, you can then call your function normally in the render by passing params to it. Works like a charm! Just make sure you set your useCallback's dependency array appropriately.
Best Solution with React >= 16
The cleanest way I've found to call functions with multiple parameters in onClick, onChange etc. without using inline functions is to use the custom data attribute available in React 16 and above versions.
const App = () => {
const onClick = (e) => {
const value1 = e.currentTarget.getAttribute("data-value1")
const value2 = e.currentTarget.getAttribute("data-value2")
const value2 = e.currentTarget.getAttribute("data-value2")
console.log("Values1", value1)
console.log("Values2", value2)
console.log("Values3", value3)
}
return (
<button onClick={onClick} data-value1="a" data-value2="b" data-value3="c" />
)
}
Above example is for a functional component but the implementation is pretty similar even in class components.
This approach doesn't yield unnecessary re-renders because you aren't using inline functions, and you avoid the hassle of binding with this.
It allows you to pass as many values as you would like to use in your function.
If you are passing values as props to your children to be used in the Child Component's onClick, you can use this approach there as well, without creating a wrapper function.
Works with array of objects as well, in cases where you want to pass the id from the object to the onClick, as shown below.
const App = () => {
const [arrState, setArrState] = useState(arr)
const deleteContent = (e) => {
const id = e.currentTarget.getAttribute("data-id")
const tempArr = [...arrState]
const filteredArr = tempArr.filter((item) => item.id !== id)
setArrState(filteredArr)
}
return (
<div>
{arrState.map((item) => (
<React.Fragment key={item.id}>
<p>{item.content}</p>
<button onClick={deleteContent} data-id={item.id}>
Delete
</button>
</React.Fragment>
))}
</div>
)
}
this example might be little different from yours. but i can assure you that this is the best solution you can have for this problem.
i have searched for days for a solution which has no performance issue. and finally came up with this one.
class HtmlComponent extends React.Component {
constructor() {
super();
this.state={
name:'MrRehman',
};
this.handleClick= this.handleClick.bind(this);
}
handleClick(event) {
const { param } = e.target.dataset;
console.log(param);
//do what you want to do with the parameter
}
render() {
return (
<div>
<h3 data-param="value what you wanted to pass" onClick={this.handleClick}>
{this.state.name}
</h3>
</div>
);
}
}
UPDATE
incase you want to deal with objects that are supposed to be the parameters. you can use JSON.stringify(object) to convert to it to string and add to the data set.
return (
<div>
<h3 data-param={JSON.stringify({name:'me'})} onClick={this.handleClick}>
{this.state.name}
</h3>
</div>
);
Simply create a function like this
function methodName(params) {
//the thing you wanna do
}
and call it in the place you need
<Icon onClick = {() => { methodName(theParamsYouwantToPass);} }/>
class extends React.Component {
onClickDiv = (column) => {
// do stuff
}
render() {
return <div onClick={() => this.onClickDiv('123')} />
}
}
I realize this is pretty late to the party, but I think a much simpler solution could satisfy many use cases:
handleEdit(event) {
let value = event.target.value;
}
...
<button
value={post.id}
onClick={this.handleEdit} >Edit</button>
I presume you could also use a data- attribute.
Simple, semantic.
Making alternate attempt to answer OP's question including e.preventDefault() calls:
Rendered link (ES6)
<a href="#link" onClick={(e) => this.handleSort(e, 'myParam')}>
Component Function
handleSort = (e, param) => {
e.preventDefault();
console.log('Sorting by: ' + param)
}
One more option not involving .bind or ES6 is to use a child component with a handler to call the parent handler with the necessary props. Here's an example (and a link to working example is below):
var HeaderRows = React.createClass({
handleSort: function(value) {
console.log(value);
},
render: function () {
var that = this;
return(
<tr>
{this.props.defaultColumns.map(function (column) {
return (
<TableHeader value={column} onClick={that.handleSort} >
{column}
</TableHeader>
);
})}
{this.props.externalColumns.map(function (column) {
// Multi dimension array - 0 is column name
var externalColumnName = column[0];
return ( <th>{externalColumnName}</th>
);
})}
</tr>);
)
}
});
// A child component to pass the props back to the parent handler
var TableHeader = React.createClass({
propTypes: {
value: React.PropTypes.string,
onClick: React.PropTypes.func
},
render: function () {
return (
<th value={this.props.value} onClick={this._handleClick}
{this.props.children}
</th>
)
},
_handleClick: function () {
if (this.props.onClick) {
this.props.onClick(this.props.value);
}
}
});
The basic idea is for the parent component to pass the onClick function to a child component. The child component calls the onClick function and can access any props passed to it (and the event), allowing you to use any event value or other props within the parent's onClick function.
Here's a CodePen demo showing this method in action.
You can simply do it if you are using ES6.
export default class Container extends Component {
state = {
data: [
// ...
]
}
handleItemChange = (e, data) => {
// here the data is available
// ....
}
render () {
return (
<div>
{
this.state.data.map((item, index) => (
<div key={index}>
<Input onChange={(event) => this.handItemChange(event,
item)} value={item.value}/>
</div>
))
}
</div>
);
}
}
There are couple of ways to pass parameter in event handlers, some are following.
You can use an arrow function to wrap around an event handler and pass parameters:
<button onClick={() => this.handleClick(id)} />
above example is equivalent to calling .bind or you can explicitly call bind.
<button onClick={this.handleClick.bind(this, id)} />
Apart from these two approaches, you can also pass arguments to a function that is defined as a curry function.
handleClick = (id) => () => {
console.log("Hello, your ticket number is", id)
};
<button onClick={this.handleClick(id)} />
Implementing show total count from an object by passing count as a parameter from main to sub components as described below.
Here is MainComponent.js
import React, { Component } from "react";
import SubComp from "./subcomponent";
class App extends Component {
getTotalCount = (count) => {
this.setState({
total: this.state.total + count
})
};
state = {
total: 0
};
render() {
const someData = [
{ name: "one", count: 200 },
{ name: "two", count: 100 },
{ name: "three", count: 50 }
];
return (
<div className="App">
{someData.map((nameAndCount, i) => {
return (
<SubComp
getTotal={this.getTotalCount}
name={nameAndCount.name}
count={nameAndCount.count}
key={i}
/>
);
})}
<h1>Total Count: {this.state.total}</h1>
</div>
);
}
}
export default App;
And Here is SubComp.js
import React, { Component } from 'react';
export default class SubComp extends Component {
calculateTotal = () =>{
this.props.getTotal(this.props.count);
}
render() {
return (
<div>
<p onClick={this.calculateTotal}> Name: {this.props.name} || Count: {this.props.count}</p>
</div>
)
}
};
Try to implement above and you will get exact scenario that how pass parameters works in reactjs on any DOM method.
I wrote a wrapper component that can be reused for this purpose that builds on the accepted answers here. If all you need to do is pass a string however, then just add a data-attribute and read it from e.target.dataset (like some others have suggested). By default my wrapper will bind to any prop that is a function and starts with 'on' and automatically pass the data prop back to the caller after all the other event arguments. Although I haven't tested it for performance, it will give you the opportunity to avoid creating the class yourself, and it can be used like this:
const DataButton = withData('button')
const DataInput = withData('input');
or for Components and functions
const DataInput = withData(SomeComponent);
or if you prefer
const DataButton = withData(<button/>)
declare that Outside your container (near your imports)
Here is usage in a container:
import withData from './withData';
const DataInput = withData('input');
export default class Container extends Component {
state = {
data: [
// ...
]
}
handleItemChange = (e, data) => {
// here the data is available
// ....
}
render () {
return (
<div>
{
this.state.data.map((item, index) => (
<div key={index}>
<DataInput data={item} onChange={this.handleItemChange} value={item.value}/>
</div>
))
}
</div>
);
}
}
Here is the wrapper code 'withData.js:
import React, { Component } from 'react';
const defaultOptions = {
events: undefined,
}
export default (Target, options) => {
Target = React.isValidElement(Target) ? Target.type : Target;
options = { ...defaultOptions, ...options }
class WithData extends Component {
constructor(props, context){
super(props, context);
this.handlers = getHandlers(options.events, this);
}
render() {
const { data, children, ...props } = this.props;
return <Target {...props} {...this.handlers} >{children}</Target>;
}
static displayName = `withData(${Target.displayName || Target.name || 'Component'})`
}
return WithData;
}
function getHandlers(events, thisContext) {
if(!events)
events = Object.keys(thisContext.props).filter(prop => prop.startsWith('on') && typeof thisContext.props[prop] === 'function')
else if (typeof events === 'string')
events = [events];
return events.reduce((result, eventType) => {
result[eventType] = (...args) => thisContext.props[eventType](...args, thisContext.props.data);
return result;
}, {});
}
I have below 3 suggestion to this on JSX onClick Events -
Actually, we don't need to use .bind() or Arrow function in our code. You can simple use in your code.
You can also move onClick event from th(or ul) to tr(or li) to improve the performance. Basically you will have n number of "Event Listeners" for your n li element.
So finally code will look like this:
<ul onClick={this.onItemClick}>
{this.props.items.map(item =>
<li key={item.id} data-itemid={item.id}>
...
</li>
)}
</ul>
// And you can access item.id in onItemClick method as shown below:
onItemClick = (event) => {
console.log(e.target.getAttribute("item.id"));
}
I agree with the approach mention above for creating separate React Component for ListItem and List. This make code looks good however if you have 1000 of li then 1000 Event Listeners will be created. Please make sure you should not have much event listener.
import React from "react";
import ListItem from "./ListItem";
export default class List extends React.Component {
/**
* This List react component is generic component which take props as list of items and also provide onlick
* callback name handleItemClick
* #param {String} item - item object passed to caller
*/
handleItemClick = (item) => {
if (this.props.onItemClick) {
this.props.onItemClick(item);
}
}
/**
* render method will take list of items as a props and include ListItem component
* #returns {string} - return the list of items
*/
render() {
return (
<div>
{this.props.items.map(item =>
<ListItem key={item.id} item={item} onItemClick={this.handleItemClick}/>
)}
</div>
);
}
}
import React from "react";
export default class ListItem extends React.Component {
/**
* This List react component is generic component which take props as item and also provide onlick
* callback name handleItemClick
* #param {String} item - item object passed to caller
*/
handleItemClick = () => {
if (this.props.item && this.props.onItemClick) {
this.props.onItemClick(this.props.item);
}
}
/**
* render method will take item as a props and print in li
* #returns {string} - return the list of items
*/
render() {
return (
<li key={this.props.item.id} onClick={this.handleItemClick}>{this.props.item.text}</li>
);
}
}
I have added code for onclick event value pass to the method in two ways . 1 . using bind method 2. using arrow(=>) method . see the methods handlesort1 and handlesort
var HeaderRows = React.createClass({
getInitialState : function() {
return ({
defaultColumns : ["col1","col2","col2","col3","col4","col5" ],
externalColumns : ["ecol1","ecol2","ecol2","ecol3","ecol4","ecol5" ],
})
},
handleSort: function(column,that) {
console.log(column);
alert(""+JSON.stringify(column));
},
handleSort1: function(column) {
console.log(column);
alert(""+JSON.stringify(column));
},
render: function () {
var that = this;
return(
<div>
<div>Using bind method</div>
{this.state.defaultColumns.map(function (column) {
return (
<div value={column} style={{height : '40' }}onClick={that.handleSort.bind(that,column)} >{column}</div>
);
})}
<div>Using Arrow method</div>
{this.state.defaultColumns.map(function (column) {
return (
<div value={column} style={{height : 40}} onClick={() => that.handleSort1(column)} >{column}</div>
);
})}
{this.state.externalColumns.map(function (column) {
// Multi dimension array - 0 is column name
var externalColumnName = column;
return (<div><span>{externalColumnName}</span></div>
);
})}
</div>);
}
});
Below is the example which passes value on onClick event.
I used es6 syntax. remember in class component arrow function does not bind automatically, so explicitly binding in constructor.
class HeaderRows extends React.Component {
constructor(props) {
super(props);
this.handleSort = this.handleSort.bind(this);
}
handleSort(value) {
console.log(value);
}
render() {
return(
<tr>
{this.props.defaultColumns.map( (column, index) =>
<th value={ column }
key={ index }
onClick={ () => this.handleSort(event.target.value) }>
{ column }
</th>
)}
{this.props.externalColumns.map((column, index) =>
<th value ={ column[0] }
key={ index }>
{column[0]}
</th>
)}
</tr>
);
}
}
I guess you will have to bind the method to the React’s class instance. It’s safer to use a constructor to bind all methods in React. In your case when you pass the parameter to the method, the first parameter is used to bind the ‘this’ context of the method, thus you cannot access the value inside the method.
1. You just have to use an arrow function in the Onclick event like this:
<th value={column} onClick={() => that.handleSort(theValue)} >{column}</th>
2.Then bind this in the constructor method:
this.handleSort = this.handleSort.bind(this);
3.And finally get the value in the function:
handleSort(theValue){
console.log(theValue);
}
Using arrow function :
You must install stage-2:
npm install babel-preset-stage-2 :
class App extends React.Component {
constructor(props) {
super(props);
this.state = {
value=0
}
}
changeValue = (data) => (e) => {
alert(data); //10
this.setState({ [value]: data })
}
render() {
const data = 10;
return (
<div>
<input type="button" onClick={this.changeValue(data)} />
</div>
);
}
}
export default App;
Theres' a very easy way.
onClick={this.toggleStart('xyz')} .
toggleStart= (data) => (e) =>{
console.log('value is'+data);
}
class TableHeader extends Component {
handleClick = (parameter,event) => {
console.log(parameter)
console.log(event)
}
render() {
return (
<button type="button"
onClick={this.handleClick.bind(this,"dataOne")}>Send</button>
);
}
}
Coming out of nowhere to this question, but i think .bind will do the trick. Find the sample code below.
const handleClick = (data) => {
console.log(data)
}
<button onClick={handleClick.bind(null, { title: 'mytitle', id: '12345' })}>Login</button>
There are 3 ways to handle this :-
Bind the method in constructor as :-
export class HeaderRows extends Component {
constructor() {
super();
this.handleSort = this.handleSort.bind(this);
}
}
Use the arrow function while creating it as :-
handleSort = () => {
// some text here
}
Third way is this :-
<th value={column} onClick={() => that.handleSort} >{column}</th>
You can use your code like this:
<th value={column} onClick={(e) => that.handleSort(e, column)} >{column}</th>
Here e is for event object, if you want to use event methods like preventDefault() in your handle function or want to get target value or name like e.target.name.
There were a lot of performance considerations, all in the vacuum.
The issue with this handlers is that you need to curry them in order to incorporate the argument that you can't name in the props.
This means that the component needs a handler for each and every clickable element. Let's agree that for a few buttons this is not an issue, right?
The problem arises when you are handling tabular data with dozens of columns and thousands of rows. There you notice the impact of creating that many handlers.
The fact is, I only need one.
I set the handler at the table level (or UL or OL...), and when the click happens I can tell which was the clicked cell using data available since ever in the event object:
nativeEvent.target.tagName
nativeEvent.target.parentElement.tagName
nativeEvent.target.parentElement.rowIndex
nativeEvent.target.cellIndex
nativeEvent.target.textContent
I use the tagname fields to check that the click happened in a valid element, for example ignore clicks in THs ot footers.
The rowIndex and cellIndex give the exact location of the clicked cell.
Textcontent is the text of the clicked cell.
This way I don't need to pass the cell's data to the handler, it can self-service it.
If I needed more data, data that is not to be displayed, I can use the dataset attribute, or hidden elements.
With some simple DOM navigation it's all at hand.
This has been used in HTML since ever, since PCs were much easier to bog.
When working with a function as opposed to a class, it's actually fairly easy.
const [breakfastMain, setBreakFastMain] = useState("Breakfast");
const changeBreakfastMain = (e) => {
setBreakFastMain(e.target.value);
//sometimes "value" won't do it, like for text, etc. In that case you need to
//write 'e.target/innerHTML'
}
<ul onClick={changeBreakfastMain}>
<li>
"some text here"
</li>
<li>
"some text here"
</li>
</ul>
I'd do it like this:
const HeaderRows = props => {
const handleSort = value => () => {
}
return <tr>
{props.defaultColumns.map((column, i) =>
<th key={i} onClick={handleSort(column)}>{column}</th>)}
{props.externalColumns.map((column, i) => {
// Multi dimension array - 0 is column name
const externalColumnName = column[0]
return (<th key={i}>{externalColumnName}</th>)
})}
</tr>
}

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