UseEffect vs useLayout in typescript

Whether you're just getting started with React or you're a seasoned pro, you've likely encountered the useEffect and useLayout hooks. These hooks are essential for managing state and side effects in your React components, but it's important to understand the differences between them.

In this blog, we'll look at the differences between useEffect and useLayout in Typescript and provide some examples of each.

What is useEffect?

useEffect is a React hook that allows you to run side effects in your components. This can include tasks such as setting up subscriptions, triggering network requests, or manipulating the DOM. It's important to note that useEffect is run after every render, so it's best to use it for tasks that don't rely on data from previous renders.

What is useLayout?

useLayout is a React hook that allows you to run layout effects in your components. This can include tasks such as measuring the size of an element, calculating positions, or computing styles. Unlike useEffect, useLayout is only run after the initial render, so it's best to use it for tasks that rely on data from previous renders.

Examples

To better understand the differences between useEffect and useLayout, let's take a look at some examples.

useEffect Example

This example shows how to use useEffect to set up a subscription to a data source:

const [data, setData] = useState<Data[]>([]);

useEffect(() => {
  const subscription = dataSource.subscribe((data) => {
    setData(data);
  });

  return () => {
    subscription.unsubscribe();
  };
});

useLayout Example

This example shows how to use useLayout to measure the size of an element:

const [dimensions, setDimensions] = useState<{ width: number; height: number }>(
  { width: 0, height: 0 }
);

useLayout(() => {
  const element = document.getElementById("element");
  const rect = element.getBoundingClientRect();
});