You can download the source code for this project from Github. This will build and launch the timer in your default browser. With this you can now open your terminal, cd to the Composi timer project and run: npm start tState('Advanced Timer') const timer = new Timer() This goes for all the React files: // Change this: import React from 'react' import PropTypes from 'prop-types' // To this: import from './components/title' import Timer from './components/Timer/timer' // Set state on component. And since Composi has no PropTypes, any imports or code using them needs to be delete. First thing to do is change the React import to import the h function from Composi. Open the Controls.js folder in your editor. Next open the React project’s components folder and copy the contents of the Timer folder to the components folder inside the Composi project’s dev folder. First copy the lib folder from the React project’s src folder over to the dev folder in the Composi project. Now you can copy the React files from the Github download to the Composi project. Copy the React Files to the Composi Project This will create a new basic Composi project on your desktop. #Unpkg import setstate from react how toIf you're looking to start using function components with hooks over class components hopefully this post has helped you understand a little bit more about how to implement them.If you don’t have it installed, you can install Composi like so: npm i -g composiĪfter that, you can create a new project: composi -n composi-advanced-timer While using functional components with hooks is the new hotness, the state management is still very similar to the class components. We can spread the current array, add the new item, and then set the current todo back to an empty string so we can clear the input. With the hook, I don't think the use of creating the list array beforehand is needed. We could have avoided this in the class component but I think the readability when using the variable is much better. The only difference we see here is that we don't create a list variable to pass into the hook. We then have the same addItem function attached to the click of our Add Item button. We use the setTodo function to set our todo value in the onChange attribute of our input. The setState function will cause the component to rerender so every time you add an item it is immediately rendered onto the page.ĭealing with the hooks in a function component seems extremely similar to the class component. Lastly at the bottom, we map through the current todoArr. After creating the list array we use the setState function to replace the current todoArr with the new one and then set the todo back to an empty string to clear the input. In the addItem function we are going to create a list variable which is is an array that spreads the current todoArr and then adds the new todo item to the end of it. We then have our Add Item button which when clicked will call our addItem function. In this example, we use the onChange attribute for our input to set the todo in our state object. One would be the array itself todoArr: and the other would be the value that we are going to be pushing into the array todo: "". When using an array in a stateful class component we need at least two keys in our state object. In these examples, we will be creating a very simple todo list. Using arrays in stateful components can be extremely powerful, especially when creating things like a todo list. Note: I have my own preference for how to deal with objects while using hooks, and as you get more familiar you may find you enjoy either the class or functional component more than the other. In this example, we've created a state = and their values.Ĭreating an object could also be accomplished using multiple useState hooks and then bundling them into an object later if needed. This state object is then modified by calling tState("new state"). Using state in a class component requires the building of a state object. While these two code snippets look similar they do have slight differences in syntax, lifecycle methods, and state management. They allow you to use state and other React features without the need to create a class. React hooks were introduced in React v16.8. Anytime you see a tState() this is how we are setting the state in a class component. This is something you will see a lot of in the examples below. The setState function is used to handle the state object in a React class component. We will also take a look at how these would be handled in class components.ĭisclaimer - I would normally create an onChange function separately but I find it easier to understand with an inline function. #Unpkg import setstate from react updateWe’re passing an empty string as a value and, to update the state of searchTerm, we have to call setState (). Let’s say we have a search component and want to display the search term a user submits. The purpose of this article is to break down the use of the useState() React hook in an easy way using strings, objects, and arrays. setState () is the only legitimate way to update state after the initial state setup.
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