This community-built FAQ covers the “Update an Input’s Value” exercise from the lesson “React Forms”.
Paths and Courses
This exercise can be found in the following Codecademy content:
Web Development
Learn ReactJS: Part II
FAQs on the exercise Update an Input’s Value
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what is the purpose of step 1 of this exercises? That is, how does adding the value attribute do anything? I tried running without it, and the h1 was still responsive to my input.
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I’m not 100% sure, but it seems that setting the value attribute to be this.state.userInput makes the Input component “controlled” (see the next exercise entitled Controlled vs Uncontrolled). The React documentation on forms says that the <input /> element has its own state (what users enter) by default. The React component also stores it as its own state. We don’t want two truths to exist. So we override the <input/> element’s state with the React component’s state.
Can someone confirm if my answer is correct?
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Here’s a StackOverflow explanation: reactjs - is value attribute necessary in a react component's input? - Stack Overflow.
Basically, it doesn’t really matter in this example but setting the value={state} is usually a good idea. It prevents something other than the input changing the state and getting the input and the state out of sync. For example, assume I have a button that sets the userInput to ‘banana.’ If I type ‘apple’ into the input, then click the button, the userInput is now set to ‘banana’ but the input still says ‘apple.’ Using value={userInput} when we click the button, the input text will change as well.
I hope this helps!
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