prettier_testfile.js

function HelloWorld({
    greeting = "hello",
    greeted = '"World"',
    silent = false,
    onMouseOver,
}) {
    if (!greeting) {
        return null;
    }

    // TODO: Don't use random in render
    let num = Math.floor(Math.random() * 1e7)
        .toString()
        .replace(/\.\d+/gi, "");

    return (
        <div
            className="HelloWorld"
            title={`You are visitor number ${num}`}
            onMouseOver={onMouseOver}
        >
            <strong>
                {greeting.slice(0, 1).toUpperCase() +
                    greeting.slice(1).toLowerCase()}
            </strong>
            {greeting.endsWith(",") ? (
                " "
            ) : (
                <span style={{ color: "grey" }}>", "</span>
            )}
            <em>{greeted}</em>
            {silent ? "." : "!"}
        </div>
    );
}