Think of it like you're just calling JavaScript functions. You can't use a for loop where the arguments to a function call would go:
return tbody(
for (let i = 0; i < numrows; i++) {
ObjectRow()
}
)
See how the function tbody is being passed a for loop as an argument – leading to a syntax error.
But you can make an array, and then pass that in as an argument:
const rows = [];
for (let i = 0; i < numrows; i++) {
rows.push(ObjectRow());
}
return tbody(rows);
You can basically use the same structure when working with JSX:
const rows = [];
for (let i = 0; i < numrows; i++) {
// note: we are adding a key prop here to allow react to uniquely identify each
// element in this array. see: https://reactjs.org/docs/lists-and-keys.html
rows.push(<ObjectRow key={i} />);
}
return <tbody>{rows}</tbody>;
Incidentally, my JavaScript example is almost exactly what that example of JSX transforms into. Play around with Babel REPL to get a feel for how JSX works.
Answer from Sophie Alpert on Stack Overflow Top answer 1 of 16
1828
Think of it like you're just calling JavaScript functions. You can't use a for loop where the arguments to a function call would go:
return tbody(
for (let i = 0; i < numrows; i++) {
ObjectRow()
}
)
See how the function tbody is being passed a for loop as an argument – leading to a syntax error.
But you can make an array, and then pass that in as an argument:
const rows = [];
for (let i = 0; i < numrows; i++) {
rows.push(ObjectRow());
}
return tbody(rows);
You can basically use the same structure when working with JSX:
const rows = [];
for (let i = 0; i < numrows; i++) {
// note: we are adding a key prop here to allow react to uniquely identify each
// element in this array. see: https://reactjs.org/docs/lists-and-keys.html
rows.push(<ObjectRow key={i} />);
}
return <tbody>{rows}</tbody>;
Incidentally, my JavaScript example is almost exactly what that example of JSX transforms into. Play around with Babel REPL to get a feel for how JSX works.
2 of 16
1201
I am not sure if this will work for your situation, but often map is a good answer.
If this was your code with the for loop:
<tbody>
for (var i=0; i < objects.length; i++) {
<ObjectRow obj={objects[i]} key={i}>
}
</tbody>
You could write it like this with map:
<tbody>
{objects.map(function(object, i){
return <ObjectRow obj={object} key={i} />;
})}
</tbody>
ES6 syntax:
<tbody>
{objects.map((object, i) => <ObjectRow obj={object} key={i} />)}
</tbody>
Thinkster
thinkster.io › tutorials › iterating-and-rendering-loops-in-react
Iterating & Rendering with Loops in React components - Thinkster
What this means is that we need to convert our array from [‘Jake’, ‘Jon’, ‘Thruster’] to · [React.createElement('li', null, ‘Jake’), React.createElement('li', null, ‘Jon’), React.createElement('li', null, ’Thruster’)] — and since we’re using JSX (thank you programming gods), it would instead look super pretty: [<li>Jake</li>, <li>Jon</li>, <li>Thruster</li>]. ... var Hello = React.createClass({ render: function() { var names = ['Jake', 'Jon', 'Thruster']; return ( <ul> {names.map(function(name, index){ return <li key={ index }>{name}</li>; })} </ul> ) } });
Loop through Array within Object React
Hi, I’m very new to React, I’m working on a project where I’m fetching data from an API then display is on a table. there is a array within the object returned and the indexes are mixed up i.e value in array [0] is ‘BMW’ and in a different object returned array [0] is ‘Grey’. ... More on forum.freecodecamp.org
0
0
August 27, 2022How do you render a component x number of times within a render statement without using a for... loop?
Simplest solution I've found: new Array(16).fill('').map((_, index) => ) Always remember to add a key to your looped component. If these are truly identical, it probably doesn't make a huge difference, but React will complain if you don't. (Also note that using the index as a key is an anti-pattern, but in this case, with elements that can't change positions between renders, it's probably safe.) More on reddit.com
30
9
August 1, 2021Loop Through Array To Create Components?
artists.map(artist => ) More on reddit.com
11
5
June 27, 2022Using anything rather than .map to render lists in JSX?
I've used for loops cos state held an array, even experimented with reduce to create a single consolidated code block of lists, but nothing else is as simple and effective as using map. More on reddit.com
45
0
February 7, 2024Videos
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DhiWise
dhiwise.com › post › mastering-react-looping-through-array-a-comprehensive-guide
Understanding React Looping Through Array
January 10, 2024 - By wrapping the map function inside curly braces within the return block of a React component, developers can loop inside React JSX and generate a new array of elements that can be rendered to the DOM.
Sentry
sentry.io › sentry answers › react › how do you loop inside react jsx?
How do you loop inside React JSX? | Sentry
You can loop over an array and ... } export default App; You can use the map() method on an array to loop through the elements and create components, or generate JSX, inside the return block....
SheCodes
shecodes.io › athena › 10518-how-to-loop-an-array-in-react-and-render-the-results
[React] - How to Loop an Array in React and Render the | SheCodes
Learn how to loop through an array in React and render it on the page, including a key for each element, using the .map() function.
Bobby Hadz
bobbyhadz.com › blog › react-loop-through-array-of-objects
Loop through an Array of Objects in React | bobbyhadz
The function we passed to the Array.map() method gets called for each element in the array. On each iteration, we set the key prop on the outermost element to a unique value, and rendered the values of the object.
Tim Mousk
timmousk.com › blog › react-loop-through-array-of-objects
How To Loop Through An Array Of Objects In React? – Tim Mouskhelichvili
March 11, 2023 - javascriptimport React from "react"; import ReactDOM from "react-dom"; const animals = [ { type: "dog", age: 2 }, { type: "cat", age: 3 } ]; const App = () => { const list = []; animals.forEach((animal, index) => { list.push( <div key={index}> <div>Type: {animal.type}</div> <div>Age: {animal.age}</div> </div> ); }); return list; }; ReactDOM.render(<App />, document.getElementById("container")); One advantage of this method is you can externalize the logic of building the list into a separate function. That way, you have a code separated into smaller pieces, AND you can reuse the function in other components. The final method is building a list of components with the for loop.
Medium
medium.com › how-to-react › different-ways-to-loop-through-arrays-and-objects-in-react-39bcd870ccf
Different ways to loop through arrays and objects in React | by Manish Mandal | How To React | Medium
October 5, 2020 - So after receiving the data from ... blank array to the response data using the React setState method. Now using the map function I am iterating the data inside the render method. I have used the arrow function for a shorter version of my code you can also use the normal javascript function. Both will give the same result. The for loop is executed ...
Dayhaysoos
dayhaysoos.com › blog › rendering-components-in-react-with-loop
Rendering components in React with a loop
This post assumes you’re beginning with React and have somewhat of an understanding of how JSX works. Let’s say the goal was to show four strings wrapped in the paragraph element. The source for these numbers would be coming from an array: const arrayOfStrings = ["Zero", "One", "Two", "Three"]; ... This is no problem at all if the data in the array is so small.
CoreUI
coreui.io › blog › how-to-loop-inside-react-jsx
How to loop inside React JSX · CoreUI
September 27, 2024 - The most common and recommended way to render lists in React is by using the map method. The map function creates a new array by calling a provided function on every element in the calling array.
Educative
educative.io › answers › how-to-implement-a-component-loop-in-react
How to implement a component loop in React
We can loop through the data array in our parent component, which will generate the list, and use the map function to render instances of our ListItem component for each element in the array. import React from 'react'; function ListItem(props) ...
GeeksforGeeks
geeksforgeeks.org › loop-inside-react-jsx
Loop Inside React JSX | GeeksforGeeks
May 8, 2024 - When working with React, you often need to render lists of items dynamically. JavaScript's map function provides a convenient way to loop through arrays and generate JSX elements for each item.
freeCodeCamp
forum.freecodecamp.org › javascript
Loop through Array within Object React - JavaScript
August 27, 2022 - Hi, I’m very new to React, I’m working on a project where I’m fetching data from an API then display is on a table. there is a array within the object returned and the indexes are mixed up i.e value in array [0] is ‘BMW’ and in a different object returned array [0] is ‘Grey’. therefore i would like to loop through this array the give a condition as to what data i want to display. is this possible and if so how? the image attached is how I’m rendering my current display but the data output is wr...
Telerik
telerik.com › blogs › beginners-guide-loops-in-react-jsx
A Beginner’s Guide to Loops in React JSX
August 18, 2022 - When I first started with React, I realized quite early that I did not know how to loop through an array and render a list of items. The most common way of doing that is with the map function that will return JSX. You will rarely need a loop ...
Pluralsight
pluralsight.com › tech insights & how-to guides › tech guides & tutorials
Iterate Through a JSON Response in JSX Render for React | Pluralsight
September 25, 2020 - Next, iterate over the data using the map() or forEach() methods or using loops. The map() method is the most commonly used function to iterate over an array of data in JSX. You can attach the map() method to the array and pass a callback function ...
Medium
medium.com › @yuvaraj.io › react-05-conditional-rendering-and-looping-through-arrays-in-react-abf5cc90120b
React 05 : Conditional Rendering and Looping Through Arrays in React | by Yuvaraj S | Medium
September 2, 2024 - STACKBLITZ LINK: https://stack... Conditional rendering and looping through arrays are essential techniques in React for creating dynamic and interactive user interfaces....
YouTube
youtube.com › watch
How to Iterate through an array in JSX - ReactJS - YouTube
Many people coming to React from our Javascript struggle to loop through data and render to the DOM. That’s where the map feature comes in. Iterate through d...
Published October 11, 2022
Upmostly
upmostly.com › home › tutorials › how to for loop in react (with examples)
How to Use For Loop in React (with Code Examples)
October 28, 2021 - In our case, we loop through the names array and output a set of <li> tags for each element in the array, thus creating a list: ... const names = ['James', 'Paul', 'John', 'George', 'Ringo']; function App() { return ( <div> {names.map(name => ( <li> {name} </li> ))} </div> ); } To ensure that each HTML element in the React DOM has a unique identifier, you’re required to provide each rendered element with, well, a unique key.
SheCodes
shecodes.io › athena › 10517-looping-through-an-array-with-react
[React] - Looping Through an Array with React - SheCodes | SheCodes
Learn how to loop through an array of items with React and use the .map function to render a list of components.
sebhastian
sebhastian.com › react-iterate-over-array
How to iterate over and render array data in React | sebhastian
December 12, 2020 - Inside a React component, you can use the map function to iterate over an array of data and return a JSX element that renders that will be rendered by React.