Gain insights into integrating TypeScript with React to improve productivity. Learn about strongly-typed props, state, and events, and set up projects using Create React App, Webpack, and Babel.

If you are a React developer and want to build your React apps faster and more robustly, this course is for you. Learn to integrate TypeScript with React, boost your productivity, and create apps that are easier to maintain.

In this course, you will learn how to utilize TypeScript’s sophisticated type system to make React development faster and your code more readable. You will learn how to create component props, state, and events that are strongly-typed, allowing you to quickly understand what you can pass and helping you avoid mistakes.

Lastly, you will set up React projects with TypeScript. First, you will learn how to do this with the Create React App tool, then how to create a React and TypeScript project with Webpack and Babel.

Using TypeScript with React

`const RedButton: React.SFC = ({ children }) => ...`

`const RedButton: React.FC = ({ children }) => ...`

`const RedButton: React.Component = ({ children }) => ...`

`const RedButton = ({ children }: {children: React.ReactNode}) => ...`

Below is a component for a red button:

```
const RedButton = ({ children }) => (
  <button style={{ backgroundColor: "red" }}>{children}</button>
);
```

What type annotation can we use to strongly type the props of the button? (There is more than one correct answer).

<p>Below is a component for a red button:</p>
<pre><code>const RedButton = ({ children }) =&gt; (
  &lt;button style={{ backgroundColor: &quot;red&quot; }}&gt;{children}&lt;/button&gt;
);
</code></pre>
<p>What type annotation can we use to strongly type the props of the button? (There is more than one correct answer).</p>


```
const Label = ({ children, color }) =>
  color === "red" || color === "blue" ? (
    <label style={{ color }}>{children}</label>
  ) : null;
```

```
type Props = {
	color: string;
  children: React.ReactNode;
}
const Label = ({ children, color }: Props) => (
  <label style={{ color }}>{children}</label>
);
```

```
type Props = {
	color: "red" | "blue";
  children: React.ReactNode;
}
const Label = ({ children, color }: Props) => (
  <label style={{ color }}>{children}</label>
);
```

The component below renders a label in a specified color. How can we use strongly-typed props so that only `"blue"` or `"red"` can be passed into the color prop?

```
const Label = ({ children, color }) => (
  <label style={{ color }}>{children}</label>
);
```

<p>The component below renders a label in a specified color. How can we use strongly-typed props so that only <code>&quot;blue&quot;</code> or <code>&quot;red&quot;</code> can be passed into the color prop?</p>
<pre><code>const Label = ({ children, color }) =&gt; (
  &lt;label style={{ color }}&gt;{children}&lt;/label&gt;
);
</code></pre>


Make `size` an optional property:

```
type Props = { size?: "small" | "large", children: React.ReactNode };
const Button = ({ children, size }: Props) => (
  <button style={{ height: size === "small" ? "20px" : "30px" }}>
    {children}
  </button>
);
```

Remove the type annotation and give the `size` prop a default:

```
const Button = ({ children, size = "small" }) => (
  <button style={{ height: size === "small" ? "20px" : "30px" }}>
    {children}
  </button>
);
```

Make `size` an optional property and give it a default:

```
type Props = { size?: "small" | "large", children: React.ReactNode };
const Button: Props = ({
  children,
  size = "small"
}: Props) => (
  <button style={{ height: size === "small" ? "20px" : "30px" }}>
    {children}
  </button>
);
```

We have a button component below that has a `size` prop to specify the height of the button. How can we allow consumers of the component not to specify the `size` prop and have it default to `"small"`?  

```
type Props = { size: "small" | "large", children: React.ReactNode };
const Button = ({ children, size }: Props) => (
  <button style={{ height: size === "small" ? "20px" : "30px" }}>
    {children}
  </button>
);
```

<p>We have a button component below that has a <code>size</code> prop to specify the height of the button. How can we allow consumers of the component not to specify the <code>size</code> prop and have it default to <code>&quot;small&quot;</code>?</p>
<pre><code>type Props = { size: &quot;small&quot; | &quot;large&quot;, children: React.ReactNode };
const Button = ({ children, size }: Props) =&gt; (
  &lt;button style={{ height: size === &quot;small&quot; ? &quot;20px&quot; : &quot;30px&quot; }}&gt;
    {children}
  &lt;/button&gt;
);
</code></pre>


```
interface Person {
  name: string;
  email: string;
}
interface Props {
  color: string;
  person: Person;
}
const PersonCard = ({ color, person }: Props) => (
  <div style={{ border: `1px solid ${color}` }}>
    <h3>{person.name}</h3>
    <a href={`mailto: ${person.email}`}>{person.email}</a>
  </div>
);
```

```
interface Props {
  color: string;
  name: string;
  email: string;
}
const PersonCard = ({ color, person }: Props) => (
  <div style={{ border: `1px solid ${color}` }}>
    <h3>{person.name}</h3>
    <a href={`mailto: ${person.email}`}>{person.email}</a>
  </div>
);
```

```
interface Person {
  name: string;
  email: string;
}
interface Props {
  color?: string;
  person?: Person;
}
const PersonCard = ({ color, person }: Props) => (
  <div style={{ border: `1px solid ${color}` }}>
    <h3>{person.name}</h3>
    <a href={`mailto: ${person.email}`}>{person.email}</a>
  </div>
);
```

We have a card component below that shows the name and email address of a person:

```
const PersonCard = ({ color, person }) => (
  <div style={{ border: `1px solid ${color}` }}>
    <h3>{person.name}</h3>
    <a href={`mailto: ${person.email}`}>{person.email}</a>
  </div>
);
```

How can we strongly-type the props for this component?

<p>We have a card component below that shows the name and email address of a person:</p>
<pre><code>const PersonCard = ({ color, person }) =&gt; (
  &lt;div style={{ border: `1px solid ${color}` }}&gt;
    &lt;h3&gt;{person.name}&lt;/h3&gt;
    &lt;a href={`mailto: ${person.email}`}&gt;{person.email}&lt;/a&gt;
  &lt;/div&gt;
);
</code></pre>
<p>How can we strongly-type the props for this component?</p>


```
type Props = {
  data: string[];
  renderItem: (item: string) => React.ReactNode;
}
export const List = ({ data, renderItem }: Props) => ( ... )
```

```
type Props = {
  data: string[];
  renderItem: () => React.ReactNode;
}
export const List = ({ data, renderItem }: Props) => ( ... )
```

```
type Props = {
  data: string[];
  render: (item: string) => React.ReactNode;
}
export const List = ({ data, render }: Props) => ( ... )
```

We have a `List` component that can be consumed as follows:

```
<List
  data={["Fred", "Bob", "Jane"]}
  renderItem={item => (
    <div>
      <span>{item}</span>
      <button>Do something</button>
    </div>
  )}
/>
```

What would strongly-typed props for this component be?

<p>We have a <code>List</code> component that can be consumed as follows:</p>
<pre><code>&lt;List
  data={[&quot;Fred&quot;, &quot;Bob&quot;, &quot;Jane&quot;]}
  renderItem={item =&gt; (
    &lt;div&gt;
      &lt;span&gt;{item}&lt;/span&gt;
      &lt;button&gt;Do something&lt;/button&gt;
    &lt;/div&gt;
  )}
/&gt;
</code></pre>
<p>What would strongly-typed props for this component be?</p>


Creating strongly-typed function props

<p>Creating strongly-typed function props</p>


In this quiz, we will test what we have learned about strongly-typed function component props with TypeScript

Why TypeScript?

Using basic types

Creating types

Working with generic types

Creating strongly-typed function component props

Creating strongly-typed function component state

Creating strongly-typed class components

Creating strongly-typed component events and event handlers

Creating strongly-typed context

Creating strongly-typed refs

Creating React projects with TypeScript using Create React App

Creating a React and TypeScript project manually

Putting everything together

Quiz