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Making a Value Persistent

Explore how to make a value persistent in React function components by using global state variables and custom getter-setter methods. Understand how to link state across multiple updates, handle user actions, and trigger re-renders to maintain consistent UI state.

Persisting the value

JavaScript supports function scope, which means that variables defined inside a function cannot be accessed from outside the function. As a result, each function has its own scope. If we invoke a function multiple times, there'll be multiple scopes. However, no matter how many times we invoke it, it wouldn't create a different output.

For our count value, we can visualize what happened with the two updates in two different scopes in the figure below.

Two function scopes for the two updates
Two function scopes for the two updates

Luckily, JavaScript supports a function scope in a way that it can access all variables defined inside the scope in which it is defined. In our case, if a variable is defined outside of the Title function (template provided below), we can ...