useState setup
const initialState = calculateValue(props)
const [someStateVal, setSomeStateValue] = React.useState(initialState)Lazy Initialization
We can lazy initialize useState with a function like this:
const getInitialState = (props) => caluclateValue(props)
const [someStateVal, setSomeStateValue] = React.useState(initialState)In this case, React will only call the function when it needs the initial value. that is once at the time of the first render.
This is called “lazy initialization.”
Play with it or test it out here!
Also published on Medium: Javascript in Plain English
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