Function rv

Example

// initialize a state variable with initial value set to 0
const positiveVar = rv(0, {
    // all options are optional

    // define custom `eq` function that will be run on every value set to determine
    // whether or not value is going to be updated
    eq: (oldValue, newValue) => newValue > oldValue && newValue >= 0,

    // define callback that's going to be run on every change
    on: val => {}
})

// alternatively, there's a handy function initializer
// all options are identical
const positiveVar = rv.fn(() => 0)

// call variable function with no arguments to get its current value
const currentValue = positiveVar()

// call variable function passing an argument in order to set it
// Won't trigger an update because the values are "equal" under this custom rule.
positiveVar(-3, {
    // override the initial `eq` function for this update call.
    eq: (oldValue, newValue) => newValue > oldValue
    // additionally, you can disable initial `eq` function by passing `false` here
    // it will use a default `eq` function which is just a strict check: `===`
    eq: false // in this case, update WILL happen
})

// you can also subscribe to value without using any hooks
const unsubscribe = positiveVar.on(newValue => console.log(newValue))

positiveVar(4) // logs: 4

unsubscribe()

positiveVar(5) // there will be no logs
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