React Props and styling
Functions have arguments , component have Props
Last updated
Functions have arguments , component have Props
Last updated
Every React element has a props object. For elements representing HTML tags, this is just an object containing DOM properties.
Props stand for Properties. They are the read-only components which work similar to the HTML attributes. Prop is a way of passing data from parent to child component.
Think of props as arguments to a function. React components are functions which return JSX (or more generally something that's render-able like React elements, null, a string, etc.). Typically, when you have a piece of code that you would like to reuse, you can place that code into a function and any dynamic values that code used before can be accepted as arguments (for example const result = 2 + 3 could be extracted to a function and accept arguments like so const result = add(2, 3)).
NOTE: Props can be anything. they can also be (and often are) strings, arrays, objects, functions, etc.
As we already know, the react components arrange the UI in the form of a tree where the parent component becomes the root and child components become branches and sub-branches. Now suppose parent component wants to send data to one of its deeply nested components. Let us say from component 1 you need to send a property to component 6. How will you do that?
You cannot pass down a property directly to the target component. This is because React follows the rule where properties have to flow down from a parent component to an immediate child component. This means you can’t skip a layer of child components when sending a property and the child components can’t send property back up to a parent as well. You can have default props in case a parent component doesn’t pass down props so that they are still set. This is why React has one-way data binding.
For example, if you want to render this HTML using ReactDOM.render():
Then you’ll need to pass in an element whose props contain one entry for each of the <a> tag’s attributes:
Simple, right? There’s just one problem:
Not all HTML attributes map directly to props.
When creating React elements, your props need to be named after DOM properties — not HTML attributes. If you’re familiar with the DOM, this shouldn’t be a problem. If not, check out the article HTML attributes vs. DOM properties.
There’s a few of these naming differences you’ll come across rather frequently:
Instead of class, you must use the className prop to set CSS classes
Instead of a for attribute on your <label> elements, you must use a htmlFor prop
Instead of passing a string for style, you must use an object with camelCased names
Instead of tabindex, you’ll need to use a tabIndex prop (note the capitalization)
Remembering these differences can be a bit of a pain. But unless you’re building rockets or medical devices, trial and error probably won’t hurt. And as a bonus, memorizing these differences will help you even outside of the React ecosystem!
Styling a React element is as simple as passing in className and/or style props.
But which one should you use?
Actually, either is fine. There are times you can’t beat the convenience of adding a short style prop, and there are times when you’ll use className to access the extra power provided by CSS.
If you want to use selectors, including pseudo-selectors like :hover, then you’ll need to use className.
And in JSX
