Beginner WordPress Developer

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An introduction to developing WordPress blocks

Block functionality

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After making any changes to your plugin file and block metadata, you can start adding the block’s core functionality.

This is usually a case of adding the block’s functionality in the editor, via the Edit component and adding how the block stores its output, via the save function.

Let’s look at what it takes to add the block’s functionality.

Adding the block’s Edit functionality

It’s often a good idea to start by building out the block’s Edit component, so it functions correctly in the editor.

At the moment, the block displays in the editor with the scaffolded text: “Copyright Date Block – hello from the editor!”, and the scaffolded styles

If you open the edit.js file in the src directory, and scroll past the imports to the bottom you’ll see the following code:

export default function Edit() {
    return (
        <p { ...useBlockProps() }>
            { __(
                'Copyright Date Block – hello from the editor!',
                'copyright-date-block'
            ) }
        </p>
    );
}

This is the code that displays the block in the editor, also known as the Edit component. There are a couple of things to note here.

The first is that the component returns what looks like a paragraph tag with some text inside it.:

return (
        <p { ...useBlockProps() }>
            { __(
                'Copyright Date Block – hello from the editor!',
                'copyright-date-block'
            ) }
        </p>
    );

This code is known as JSX, and it’s a special syntax that looks like HTML, but it’s actually JavaScript. So while the <p> tags might look like typical HTML paragraph tags, you can see that there is some code inside the tags, which is wrapped in curly braces {}.

The curly braces are used to indicate that the code inside them should be evaluated as JavaScript, and the result should be inserted into the JSX.

Learning about how JSX works is outside the scope of this lesson, but you can learn more about JSX on the React website.

At this stage, what’s important is to note that the code returned by the Edit component is wrapped in a single container element. This is the parent container of this component, and any React component must only return a single parent container. This means you can’t return, for example, two <p> tags, or a <p> tag and a <div> tag, without ensuring they are inside one parent container.

Depending on your code editor, if you do this, you might see all kinds of red warnings.

The second thing to note is the use of the useBlockProps function. This is a special function known as a React hook that is used to fetch the block’s attributes.

You’ll see useBlockProps it has the three dots ... before it, which is known in JavaScript as the spread syntax. This takes the properties of an object and adds the object’s key-value pairs to whatever it’s being applied to.

Because useBlockProps returns an object with properties and values, the use of the spread syntax applies the properties and their values as attributes to the parent container.

Lastly, you will note that this scaffolded code is using the WordPress __() function. This is a special function that allows text to be translated for different languages, also known as Internationalization.

You can read more about Internationalization in the WordPress Developer documentation.

For now, update the component to return something more appropriate to the requirements of your block. For example:

return (
    <p { ...useBlockProps() }>
        { __(
            'Copyright',
            'copyright-date-block'
        ) }
        © 2019 - 2024
    </p>
);

For the copyright symbol, you can use the &copy; HTML entity, which will be converted to the right symbol when it’s rendered.

If you’re wondering, the reason the symbol and year is rendered outside the __() function is because you only need to make the word “Copyright” translatable.

You probably don’t want to hardcode that end date though, so you can use some JavaScript to get the current year as a variable, and replace the year with the variable.

export default function Edit() {
    const currentYear = new Date().getFullYear().toString();
    return (
        <p { ...useBlockProps() }>
            { __(
                'Copyright',
                'copyright-date-block'
            ) }
            © 2019 - { currentYear }
        </p>
    );
}

Once you’ve made the changes, save the file, and let the build run, or run the build command manually.

When you add the block to a post or page, you should see the block now displays the output you defined.

Adding the block’s save functionality

The next step is to update the block’s save functionality, so it renders correctly on the front end.

Right now, when you preview the block, it’s still showing the scaffolded text.

The save function in the save.js file is what is run every time the block is saved in the Editor. This is the content that is stored in the post_content field in the database, and rendered on the front end.

Open the save.js file in the src directory, and you’ll see the following code:

export default function save() {
    return (
        <p { ...useBlockProps.save() }>
            { 'Copyright Date Block – hello from the saved content!' }
        </p>
    );
}

This is very similar to what was scaffolded in the Edit component, with a couple of differences.

One difference is that only a specific subset of the block’s properties are applied to the parent container, via useBlockProps.save().

This is because the save function is only concerned with the properties that are relevant to the front end, and not the editor.

The other difference is that the code inside the parent tag is all on one line.

This is mostly irrelevant to the block’s actual functionality, and it just shows a different way to write the same code. Some developers prefer to split out the code onto multiple lines, as it makes it more readable in some circumstances.

So you can update the save function to return the same content as the Edit component.

export default function save() {
    const currentYear = new Date().getFullYear().toString();
    return (
        <p { ...useBlockProps.save() }>
            { 'Copyright' } © 2019 - { currentYear }
        </p>
    );
}

Once the updated block has been built, add the block to a post, and preview it. You should see the block now displays the saved markup.

Additional resources

To read more about building your Edit and save functionality, take a look at the Edit and Save reference guide in the Block Editor handbook.