ReactDOM.render and React.createElement

The first thing we need to do is we need to include the libraries that are already being brought in for us, and that’s React and ReactDOM. Now react is what we are going to be focusing this course on, and that’s the api for components. ReactDOM is what helps us connect that to a website. Each platform has an independent package. Now for us that’s going to be ReactDom since we’re working on a web project, so let’s include those into our project now. First, we’re going to import React from react. This is assigning a local identity of React from our imported mpm package, and we’re going to import ReactDOM the same from the mpm package react-dom. Great! Now it’s a little more stable and less refreshy. Now, from these packages we’re going to learn about just two things. We’re going to learn about React.createElement and ReactDOM.render. These are the two functions that we are going to cover in this lesson, and they are all that we need to make a React app on the web. We’re already getting helpful errors saying that we aren’t using ReactDOM.render correctly. It’s pulling to the line, line 6. Now the way ReactDOM works is that it takes a what and a where, and it’s going to take that what and render it into the where. This project already has an HTML file with an empty div with an id of root, and that will be our where. So let’s collect that with just some regular old Javascript. [Example]. I am groot. Now that we have our where to find, we need to work on the what. And the what is going to be our new React element. The first argument for a React element is going to be the type of element that we want to render. Any type of HTML tag will work here when wrapped in a string like this,. The second argument is going to be the options for that element, so these are going to be like className and id and any data attributes. Things of that nature. Finally, in the last position we have the inner text, or the children of this element, and I’m just going to say Hello React!. And just like that, with just these few lines of code, we have our first working React app.