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Hello I have a component which doesnt return anything. Im following a tutorial and the person is using newer syntax which confuses me a bit. The component looks like this:

const Alert = ({alerts}) => alerts !== null && alerts.length > 0 && alerts.map(alert => (<div key={alert.id} className={`alert-${alert.type}`}>{alert.msg}</div>));

I simply want to know how to write this without it being single line. So i can see what's going on. Much appreciated in advance. For as far as i am aware you always need to return something.

const Alert = ({ alerts }) => {
  if (alerts !== null && alerts.length > 0) {
    return alerts.map(alert => (
      <div key={alert.id} className={`alert-${alert.type}`}>
        {alert.msg}
      </div>
    ));
  }
  return null
};

Things at play here are:

  1. Arrow Functions
  2. Array.Map
  3. JSX
  4. Template Literals

Basically its a component that takes in an alerts property (Array) as a prop (<Alert alerts={[...]} />). It checks whether the passed array is present and is not empty and then maps over it. For every item in the array, we are rendering a div containing the alert message.

Hope this helps!

one-line React component for conditionally wrapping children · GitHub, one-line React component for conditionally wrapping children. conditionalwrap.js . import React from 'react';. const ConditionalWrap = ({condition, wrap,  I needed a one-line solution branching in a ternary operator to keep my code nicely indented. {foo ? `First line of text Second line of text` : `Single line of text`} Sublime syntax highlighting helps highlight the line-break character:

Very roughly (i.e., untested):

const Alert = ({alerts}) => {
  if ((alerts === null) || (alerts.length === 0)) { 
    return null
  }

  return alerts.map(alert => (
    <div
      key={alert.id}
      className={`alert-${alert.type}`}
    >
      {alert.msg}
    </div>
  ))
}

Stateless Functional Components, I use this syntax when my component fits on one line const ListItem = (props) => < li className="list-item">{props.item.name}</li>; // I use this  In React, mutable state is typically kept in the state property of components, and only updated with setState(). We can combine the two by making the React state be the “single source of truth”. Then the React component that renders a form also controls what happens in that form on subsequent user input.

const Alert = ({alerts}) => {
  if (!alerts || !alerts.length) return null

  return (
    <>
      {alerts.map(alert => (
        <div key={alert.id} className={`alert-${alert.type}`}>{alert.msg}</div>
      )}
    </>
  )
}

Conditional Rendering – React, Element Variables. You can use variables to store elements. This can help you conditionally render a part of the component while the rest of the output doesn't  Handling newlines with React Suppose you have a Javascript variable containing multiple lines of text that you want to render in your React component. More or less you would have the following code: const text = `This is a long string of text and it includes new line characters.

I think what you are struggling with is generally the one-liner syntax, which doesn't need a return if there are no braces present. What I mean is that this line

return alerts.map(alert => {
  return (<div key={alert.id} className={`alert-${alert.type}`}>{alert.msg} </div>)
})

Would be the same as this line

return alerts.map(alert => (<div key={alert.id} className={`alert-${alert.type}`}>{alert.msg} </div>))

The Best React Examples, React (also known as React.js) is one of the most popular JavaScript front There are many ways to declare components when using React.js. lines in a single JSX expression, write the code within a single parenthesis. Components in React. What do pure functions and functional programming have to do? Well, let’s see if we can derive their relationship… As you can read in its documentation, React is a JavaScript library for creating user interfaces through small pieces of code called “Components.” This is the first component you’ll see in their tutorial:

Everything as a Component in ReactJS, The component can be created with ES6 syntax in a single line, like this: 1 const HelloWorld = () => <div>This is single line component</div>;. Single line Grid list. This example demonstrates a horizontal scrollable single-line grid list of images. Horizontally scrolling grid lists are discouraged because the scrolling interferes with typical reading patterns, affecting comprehension. One notable exception is a horizontally-scrolling, single-line grid list of images, such as a gallery.

Airbnb React/JSX Style Guide, Only include one React component per file. if props fit in one line then keep it on the same line <Foo bar="bar" /> // children get indented normally <Foo  I was building a React Chat Room Component for my side-project. I don’t think I will be able to launch soon due to a lot of things I would love to chat about. Instead of letting this sit it my

7 Architectural Attributes of a Reliable React Component, Make your components decoupled, focused on a single task, well tested. The thin line of correctness. Unfortunately, it's  One frequently used form control is textarea, which is used to get multi-line input from a user. It's different from a normal text input, which allows only single-line input. A good example of a use case for textarea is an address field.

Comments
  • Put line breaks in? Or break up the logic into reasonable chunks (essentially a guard clause) and if it gets past that return the alert mapping? What's the specific issue?
  • This does return something. It basically checks if any alerts exists. If so, it returns a div(s) containing the alert message(s).
  • Follow another tutorial, dont seem like instructor is doing any good by using one liner to its readers/students
  • Unrelated, but I'd treat the guard clause as an explicit guard clause, e.g., flip the logic around. Guards are "gateways" to the mainline code.
  • @DaveNewton you should explain that in your answer, otherwise, it's just a code snippet.
  • @DaveNewton Thats right, but the OP asked us to simplify their given code, adding something from my side could have problems in understanding. In my opinion.
  • @AjayGupta shrug IMO making guard clauses "stand out" from the mainline code is a simplification, and in this case, makes the logic easier to understand.
  • @DaveNewton Makes sense. Will keep that in mind. Thanks! :)
  • The fragment is useless. You can return an array directly.