I created a component with several div elements.
By adding a ?goto= parameter to the url I want to scroll the the relevant element. I now solved that with const itemsRef = useRef([]);.
My main concern now is if that's the right and performance efficient approach with itemsRef.current[element.id] = el. element.id will be unique for each element.
I also found packages such as: https://github.com/Macil/react-multi-ref
But I don't see the disadvantage of my approach yet.
Here you can find my current solution in action: https://codesandbox.io/s/scrolltoref-w5i7m?file=/src/Element.js
import React, { useRef, useEffect, useState } from "react";
import clsx from "clsx";
const blueprint = [
{
id: "3mD59WO",
name: "AUDITORIUM",
position: 0,
rooms: [
{
id: "zR8Qgpj",
name: "Audimax",
subtitle: null,
details: null,
position: 0,
elements: [
{
id: "1jLv04W",
position: 0,
type: "daily",
element: "listing_large",
properties: {
meetingId: null,
capacity: 6
}
},
{
id: "1jLv12W",
position: 1,
type: "daily",
element: "listing_large",
properties: {
meetingId: null,
capacity: 6
}
}
]
}
]
},
{
id: "4mDd9WO",
name: "FOYER",
position: 1,
rooms: [
{
id: "4R8Qgpj",
name: "Speakers Table",
subtitle: null,
details: null,
position: 0,
elements: [
{
id: "2jLv04W",
position: 0,
type: "daily",
element: "listing_large",
properties: {
meetingId: null,
capacity: 6
}
},
{
id: "2jLv12W",
position: 1,
type: "daily",
element: "listing_large",
properties: {
meetingId: null,
capacity: 6
}
}
]
}
]
}
];
export default function Query() {
const itemsRef = useRef([]);
const [currentRef, setCurrentRef] = useState();
useEffect(() => {
const scrollToRef = ref => {
window.scrollTo(0, ref.offsetTop);
};
const goto = "1jLv12W"; // This will become an URL parameter ?goto=:someID in the final version
const ref = itemsRef.current[goto];
setCurrentRef(ref); // This is needed to change the className to highlight
scrollToRef(ref); // Here I assign the ref and the component should scroll to that ref
}, []);
return (
<div key="element">
{blueprint.map(floor => (
<div key={floor.id} style={{ marginTop: 50 }}>
Floor: {floor.name} <br />
<br />
{floor.rooms.map(room => (
<div key={room.id}>
Room Name: {room.name}
<br />
{room.elements.map(element => (
<div
ref={el => (itemsRef.current[element.id] = el)}
className={clsx({
highlight:
currentRef && currentRef === itemsRef.current[element.id]
})}
key={element.id}
style={{ backgroundColor: "green", marginTop: 100 }}
>
ElementID: {element.id}
<br />
</div>
))}
</div>
))}
</div>
))}
</div>
);
}
That's the right approach, usually, you will see useRef([]) when handling multiple animations in a page, and that's exactly how it's done itemsRef.current[element.id] = el.
My main concern now is if that's the right and performance efficient approach
That's directly related to "Why Premature Optimization Is the Root of All Evil".
Premature optimization is spending a lot of time on something that you may not actually need.
You trying to optimize before you have any performance issues. Focus on delivering the product and clean code, find a time for optimization when you actually measured it.
We also don’t want to waste an enormous amount of time doing performance optimization on things that don’t matter. Many development teams get caught up in focusing on optimizing for performance and scale before they have validated their new product functionality.
useRef is basically the same as doing useState({ current: <value you pass in> });
Given your use case, what you have done is sufficient however I would change use ref to initialise with an object since that is what you are actually using as oppose to an array:
const itemsRef = useRef({});
Your code still works but may potentially give you some unexpected behaviour since assigning properties to an array can be a bit weird and is definitely not what you intend to do anyway.
For example with an array you are actually doing this:
[]["<some id>"] = el; // very weird!
vs an object:
{}["<some id>"] = el
Related
I'm writing a component that renders itself inside recursively and is data-driven
Attaching my sandbox snippet, as it will be easier to see there.
This is my data:
var builderStructureData = [
{
id: 123,
value: 3,
children: []
},
{
id: 345,
value: 5,
children: [
{
id: 4123,
value: 34,
children: [
{
id: 342342,
value: 33,
children: []
}
]
},
{
id: 340235,
value: 3431,
children: [
{
id: 342231342,
value: 3415,
children: []
}
]
}
]
}
];
and it renders like this:
This is my App.js:
import { useState } from "react";
import "./App.css";
import Group from "./components/group";
import builderStructureData from "./components/builderStructureData";
function App() {
const [builderStructure, setBuilderStructure] = useState(
builderStructureData
);
return (
<div className="App">
{builderStructure.map((x) => {
return <Group key={x.id} children={x.children} value={x.value} />;
})}
</div>
);
}
export default App;
And this is my recursive component:
import React from "react";
export default function Group(props) {
let childrenArray = [];
if (props.children) {
props.children.map((x) => childrenArray.push(x));
}
return (
<div className="group" draggable>
<p>this is value: </p>
<input value={props.value} readOnly={true}></input>
<button>Add Group</button>
{childrenArray.map((x) => {
return <Group key={x.id} children={x.children} value={x.value} />;
})}
</div>
);
}
I can render the components based on the data, and it seems to be handling recursion fine. I need to store the state on the App.js page and be able to change it from within child components. For example, if I update the "value" field of the component with ID = 342342, I want it to update that corresponding object in the state no matter how deeply nested it is, but not sure how to do that as it is not as simple as just passing a prop.
Am I taking the right approach with my code snippet? How can I do the state update?
I would advise the state normalization approach - here is an example for redux state - https://redux.js.org/usage/structuring-reducers/normalizing-state-shape - but you can use this approach with your state. So - your state will look like this:
state = {
items: {
[123]: {
id: 123,
value: 3,
childrenIds: []
},
[345]: {
id: 345,
value: 5,
childrenIds: [4123, 340235]
},
[4123]: {
id: 4123,
value: 34,
parentId: 345,
childrenIds: [342342]
},
[342342]: {
id: 342342,
value: 33,
parentId: 4123,
childrenIds: []
},
[340235]: {
id: 340235,
value: 3431,
parentId: 345,
childrenIds: [342231342]
},
[342231342]: {
id: 342231342,
value: 3415,
parentId: 340235
childrenIds: []
}
}
}
Here the field "childrenIds" is an optional denormalization for ease of use, if you want - you can do without this field. With this approach, there will be no problem updating the state.
You are thinking this in a wrong way, it should be very easy to do what you want.
The most imported thing is to make a little small changes in Group
Please have a look
import React from "react";
export default function Group(props) {
const [item, setItem] = React.useState(props.item);
let childrenArray = [];
if (item.children) {
item.children.map((x) => childrenArray.push(x));
}
const updateValue = ()=> {
// this will update the value of the current object
// no matter how deep its recrusive is and the update will also happen in APP.js
// now you should also use datacontext in app.js togather with state if you want to
// trigger somethings in app.js
item.value =props.item.value= 15254525;
setState({...item}) // update the state now
}
return (
<div className="group" draggable>
<p>this is value: </p>
<input value={item.value} readOnly={true}></input>
<button>Add Group</button>
{childrenArray.map((x) => {
return <Group item={x} />;
})}
</div>
);
}
The code above should make you understand how easy it is to think about this as an object instead of keys.
Hop this should make it easy for you to understand
I was trying to add a new element of array to the list with update of one property (id). I want to make it 1 more than length of array.
But I get some weird outputs, with add every new object. All elements are getting array.length +1 value.
I made several variations of this code with let, const or even operating directly on this.state.produktsToBuy, and every time I got the same output
handleAddToShop = (produktToBuy) => {
const id = this.state.produktsToBuy.length+1;
produktToBuy.id = id + 1;
const produktsToBuy = this.state.produktsToBuy;
produktsToBuy.push(produktToBuy);
this.setState({produktsToBuy});
};
I Should get the output as 1,2,3,4,5,6,7
But on the end I get 7,7,7,7,7,7
Make sure you're not mutating the state directly. In JS, objects are a reference type. When you assign this.state.produktsToBuy to const produktsToBuy and push something to produktsToBuy, you're actually pushing to the original this.state.produktsToBuy and you modify the state.
You can use the spread operator (...) to create a shallow copy of the state (produktsToBuy):
class App extends React.Component {
state = {
items: [
{ name: "test item 1", price: 4.99 },
{ name: "test item 2", price: 7.99 },
{ name: "test item 3", price: 19.99 }
],
produktsToBuy: []
};
handleAddToShop = (produktToBuy) => {
this.setState((prev) => ({
produktsToBuy: [
...prev.produktsToBuy,
{
...produktToBuy,
id: prev.produktsToBuy.length + 1
}
]
}));
};
render() {
return (
<div className="App">
<div style={{ display: "flex" }}>
{this.state.items.map((item) => (
<div
key={item.name}
style={{
border: "1px solid #ccc",
margin: "1rem",
padding: "1rem",
textAlign: "center"
}}
>
<h3>{item.name}</h3>
<p>${item.price}</p>
<button onClick={() => this.handleAddToShop(item)}>Add</button>
</div>
))}
</div>
<pre>{JSON.stringify(this.state.produktsToBuy, null, 2)}</pre>
</div>
);
}
}
ReactDOM.render(<App />, document.getElementById('root'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<div id="root"></div>
You should be maintaining all of the previous state if there's anything other than just the produktsToBuy. Also, you always need the functional form of setState if anything you're setting is dependent on the previous state(as is OFTEN the case). And, like Zsolt said, you never mutate the state directly in React. Here's my answer (very similar to #Zsolt Meszaros'). Note: .concat creates a new array, so we don't have to worry about mutating the original.
handleAddToShop = (produktToBuy) => {
this.setState((prevState) => {
const { produktsToBuy } = prevState;
return {
...prevState,
produktsToBuy: produktsToBuy.concat([
{
...produktToBuy,
id: produktsToBuy.length + 1,
},
]),
};
});
};
I'm trying to create a glossary component in React, that allows me to filter only the glossary terms that I need for a specific unit learning. I do have two different datas array, one for the glossary terms, and one for the units. This is my glossary data file:
{
id: 1,
order: 1,
term: "Mario",
content: "It's a meeee"
},
{
id: 2,
order: 2,
term: "Luigi",
content: "Okie dokie!"
},
{
id: 3,
order: 3,
term: "Peach",
content: "Thank you, Mario!"
},
{
id: 4,
order: 4,
term: "Bowser",
content: "No one asks for a trap faster than a plumber!"
},
{
id: 5,
order: 5,
term: "Ganondorf",
content: "How dare you attempt to wound the Demon King!"
}
This is my unit data file:
const units = [
{
order: 1,
glossaryTermsRequired: [1,2,3]
},
{
order: 2,
glossaryTermsRequired: [4,5]
}
]
Now this is my glossary component:
const Glossary = ({ glossaryId, glossaryTerm }) => {
const [isOpen,setIsOpen]=useState(false)
useEffect(()=>{
insertGlossaryTerm()
})
return (
<>
<span onClick={()=>setIsOpen(true)} className="glossaryTerm">{glossaryTerm}</span>
<Sidebar closeSidebar={()=>setIsOpen(false)} isOpen={isOpen}/>
</>
);
The glossary component take two props, the id and the term string. My aim is to click on the glossary and show those required terms in the sidebar that will open on click. Now for example, if I click on the Term Bowser, how can i get to show all the terms for that required unit?(4,5 unit 2)
THank you guys
const Glossary = ({ glossaryId, glossaryTerm }) => {
const [isOpen,setIsOpen]=useState(false);
const [sidebarTerms, setSidebarTerms] = useState([]);
useEffect(()=>{
if (isOpen)
insertGlossaryTerm()
}, [isOpen])
const insertGlossaryTerm = () => {
let unit = units.find(u => u.glossaryTermsRequired.indexOf(4)>=0);
if (unit) {
let termArray = unit.glossaryTermsRequired.map(id => elements[id].term);
setSidebarTerms(termArray);
}
}
return (
<>
<span onClick={()=>setIsOpen(true)} className="glossaryTerm">{glossaryTerm}</span>
<Sidebar closeSidebar={()=>setIsOpen(false)} isOpen={isOpen} terms={sidebarTerms}/>
</>
);
Explanation:
a state to manage related terms has been created. It's a list of strings
when span is clicked, the sidebar is opened
useEffect is triggered as the isOpen state changes. Searches related terms and stores them in the related state
state is connected with Sidebar so it received via props the related terms, ready to be displayed
To make it work you need to create a global object in my example called elements, that is a key-value JSON object where the key is the id of the element, and the value is the element itself.
Example:
{
'1': {
id: 1,
order: 1,
term: "Mario",
content: "It's a meeee"
},
'2': {
id: 2,
order: 2,
term: "Luigi",
content: "Okie dokie!"
},
...
}
This avoids your application to loop through the whole list of elements to find those with the right id.
Then, you need to have units object visible too.
Improvements:
you can trigger before the insertGlossaryTerm() than the isOpen() function
if a terms can be in more than one unit, then you need to substitute .find function with a .filter
This question already has answers here:
What are the differences (if any) between ES6 arrow functions and functions bound with Function.prototype.bind?
(3 answers)
Why and when do we need to bind functions and eventHandlers in React?
(2 answers)
Closed 2 years ago.
I have simple react page showing a Tree component and a series of fields. Right now I have the Tree hardcoded, but the fields as passed in as props. Also passed in as props are two parent callbacks. One for the Tree onSelect and one for the <input> onChange event. In both cases, the specific 'on' Event is a local function that in turn calls the parent's callback. This is all working....
In both cases the local functions reference the 'this' variable. In one local function, the Tree onSelect', I had to use the '.bind(this)' way but, in the other I did not. Both local functions can access the 'this.props.' values. However, if I remove the '.bind(this)' from the one used in the Tree component it fails. The 'this' is undefined.
I am new to react, so I'm just trying to figure what goes where. I'm guessing this has something to do with the Tree being a component and the <input> as something more basic?
Thanks for any insights...
import React, { Component } from "react";
import Tree from '#naisutech/react-tree'
import './RecipePage.css';
class RecipePage extends Component {
constructor(props){
super(props);
this.state = { items: props.items,};
}
onMySelect (props) {
debugger;
const items = this.state.items.slice();
console.log("HI" , props);
}
handleChange = ({ target }) => {
debugger;
const items = this.state.items.slice();
items[parseInt(target.id)+1].defaultValue = target.value;
this.setState({items: items,});
var props = {items, target};
this.props.onInputChanged(props); // call the parent's update function send relavent data.
};
render() {
const t8000 = [
{
label: 'Gauge 1',
id: 1234,
parentId: null,
items: null
},
{
label: 'Target',
id: 1236,
parentId: 1234,
items: null
},
{
label: 'Gage Factor',
id: 5678,
parentId: 1234,
items: null
},
{
label: 'Gauge 2',
id: 1235,
parentId: null,
items: null
},
{
label: 'Target',
id: 2236,
parentId: 1235,
items: null
},
]
const myTheme = {
'my-theme': {
text: '#161616',
bg: '#f1f1f1',
highlight: '#cccccc', // the colours used for selected and hover items
decal: 'green', // the colours used for open folder indicators and icons
accent: '#f1f1f1' // the colour used for row borders and empty file indicators
}
}
return(
<div id="recipePage" className="recipeMenu" >
<div className="closeButton" >
<img src={require('./../CommonImages/closeButton_W_90x90.png')} height="90px" onClick={() => this.props.close()} alt="Menu buttons"></img>
<Tree nodes={t8000} onSelect={this.onMySelect.bind(this)} theme = {'my-theme'} customTheme={myTheme} />
<form>
<fieldset>
<legend>this.state.items[0].label}</legend>
{this.state.items.map((item, key) =>(
<div className={item.show===1 && key!==0 ?"ShowInputs":"HideInputs"}>
<label htmlFor={item.id}>{item.label} </label>
<input type="text" name={item.id}
id={item.id} value={item.defaultValue}
onChange={this.handleChange} />
</div>
))}
</fieldset>
</form>
</div>
</div>
);
}
}
export default RecipePage;
i am planning to build a generic filter like Gbif Have.
My question is how to approach this problem.
I like to use ReactJs for this project.
What other technology i need to look into along with React and redux in order to design such a generic filter.
I try to design this filter using React and redux only.
In my approach, i try to maintain the query parameter inside the state variable of the get_data method, in which i am fetching the data from the server. As somebody click on any filter button, then i pass custom event from that filter component along with query parameter and handle this event in get_data method. In get_data method again i am saving this value in get_data state parameter and again getting the new filtered data.
Now the Problem with above approach is that as the number of parameter increases it become very difficult to maintain.
my get_data constructor look like this.
constructor(props){
super(props);
this.state={
params:{
max:10,
offset:0,
taxon:[],
sGroup:[],
classification:undefined,
userGroupList:[],
isFlagged:undefined,
speciesName:undefined,
isMediaFilter:undefined,
sort:"lastRevised",
webaddress:""
},
title:[],
groupName:[],
userGroupName:[],
view:1
}
this.props.fetchObservations(this.state.params)
this.loadMore=this.loadMore.bind(this);
};
The way i am getting data from filter component is something like this.
this is my handleInput method which fire onSelect method from one of the filter.
handleInput(value,groupName){
this.setState({
active:true
})
this.props.ClearObservationPage();
var event = new CustomEvent("sGroup-filter",{ "detail":{
sGroup:value,
groupName:groupName
}
});
document.dispatchEvent(event);
};
the way i am handling this event in my get_data component is look something like this.
sGroupFilterEventListner(e){
const params=this.state.params;
if(!params.sGroup){
params.sGroup=[];
}
console.log("params.sGroup",params.taxon)
params.sGroup.push(e.detail.sGroup)
params.sGroup=_.uniqBy(params.sGroup)
const groupName=this.state.groupName;
var titleobject={};
titleobject.sGroup=e.detail.sGroup;
titleobject.groupName=e.detail.groupName;
groupName.push(titleobject);
let newgroupname=_.uniqBy(groupName,"sGroup")
params.classification=params.classification;
let isFlagged=params.isFlagged;
let speciesName=params.speciesName;
let MediaFilter=params.isMediaFilter;
let taxonparams=params.taxon;
taxonparams= taxonparams.join(",");
let sGroupParams=params.sGroup;
sGroupParams=sGroupParams.join(",");
let userGroupParams=params.userGroupList;
userGroupParams=userGroupParams.join(",");
let newparams={
max:10,
sGroup:sGroupParams,
classification:params.classification,
offset:0,
taxon:taxonparams,
userGroupList:userGroupParams,
isFlagged:isFlagged,
speciesName:speciesName,
isMediaFilter:MediaFilter,
sort:params.sort
}
this.props.fetchObservations(newparams);
this.setState({
params:{
max:10,
sGroup:params.sGroup,
classification:params.classification,
offset:0,
taxon:params.taxon,
userGroupList:params.userGroupList,
isFlagged:isFlagged,
speciesName:speciesName,
isMediaFilter:MediaFilter,
sort:params.sort
},
groupName:newgroupname
})
}
I registered and unRegistered the sGroupFilterEventListner in my componentDidMount and componentunmount method.
Presently i am also not considering the case where if somebody type in url bar, the filter panel change automatically.
Please consider all the above scenario and suggest me a generic way to do the same. thanks.
My Current Filter Panle look like this
Here's a quick example (React only, no Redux) I whipped up with a dynamic number of filters (defined in the filters array, but naturally you can acquire that from wherever).
const filters = [
{ id: "name", title: "Name", type: "string" },
{
id: "color",
title: "Color",
type: "choice",
choices: ["blue", "orange"],
},
{
id: "height",
title: "Height",
type: "choice",
choices: ["tiny", "small", "big", "huge"],
},
{
id: "width",
title: "Width",
type: "choice",
choices: ["tiny", "small", "big", "huge"],
},
];
const filterComponents = {
string: ({ filter, onChange, value }) => (
<input
value={value || ""}
onInput={e => onChange(filter.id, e.target.value)}
/>
),
choice: ({ filter, onChange, value }) => (
<select
value={value || ""}
onInput={e => onChange(filter.id, e.target.value)}
size={1 + filter.choices.length}
>
<option value="">(none)</option>
{filter.choices.map(c => (
<option value={c} key={c}>
{c}
</option>
))}
</select>
),
};
class App extends React.Component {
constructor(props) {
super(props);
this.state = { filters: {} };
this.onChangeFilter = this.onChangeFilter.bind(this);
}
onChangeFilter(filterId, value) {
const newFilterState = Object.assign({}, this.state.filters, {
[filterId]: value || undefined,
});
this.setState({ filters: newFilterState });
}
renderFilter(f) {
const Component = filterComponents[f.type];
return (
<div key={f.id}>
<b>{f.title}</b>
<Component
filter={f}
value={this.state.filters[f.id]}
onChange={this.onChangeFilter}
/>
</div>
);
}
render() {
return (
<table>
<tbody>
<tr>
<td>{filters.map(f => this.renderFilter(f))}</td>
<td>Filters: {JSON.stringify(this.state.filters)}</td>
</tr>
</tbody>
</table>
);
}
}
ReactDOM.render(<App />, document.querySelector("main"));
body {
font: 12pt sans-serif;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
<main/>
(originally on https://codepen.io/akx/pen/JyemQQ?editors=0010)
Hope this helps you along.