hydroxide

Hydroxide

Reactive core of the Hydroxide Framework

Creating State with reactive

creates a "reactive" value. Whenever it is updated using any of the updator methods, it automatically updates anything that uses it.

reactive value is a function that when called returns the current value it

const count = reactive(0)

count() // 0

JSX where you use the reactive; gets updated whenever the reactive is updated

function Counter() {
  const count = reactive(0)

  setInterval(() => {
    count.set(count() + 1)
  })

  return <p> count is {count()} </p>
}

Updating State

Reactive.set

sets a new value for the reactive

count.set(10)

Reactive.do

Reactive.do takes a transformer function as argument. It is used when you want to assign new value using the previous current value of reactive.

count.do(v => v + 1)

reactive(...path) to perform a deep update

if you want to update a value deep in a nested object, call the reactive with the path to the value and use the reactive methods to update it.

const user = reactive({
  name: 'John Doe',
  address: {
    street: 'Main St',
    city: 'New York'
  },
  todos: [
    { task: 'Buy milk', done: true },
    { task: 'Buy Groceries', done: false }
  ]
})

// update street address of the user
user('address', 'street').set('Broadway')

// toggle first task of the user
user('todos', 0, 'done').do(v => !v)

Special State Management APIs for Arrays

Take this state for example:

const todos = reactive([
  { task: 'Buy milk', done: true },
  { task: 'Buy Groceries', done: false },
  { task: 'Grab some snacks', done: false }
])

Here is the list of array methods to perform all kinds of updates

Reactive.push

push the item at the end of array

todos.push({ task: 'Eat Pizza', done: false })

Reactive.insert

insert the item at the specified index

todos.insert(1, { task: 'Write Code', done: true })

Reactive.remove

remove the item at given index, optional second argument is the number of items to remove (default is 1)

// remove 1 todo at index 2
todos.remove(2)

// remove 2 todo at index 3
todos.remove(2, 3)

Reactive.swap

swap the items at given indices

// swap the items at index 2 and 3
todos.swap(2, 3)

Reactive.pop

removes the last item from the array

optional second argument is the number of items to remove (default is 1)

// remove 1 item at the end of array
todos.pop()

// remove 3 items at the end of array
todos.pop(3)

Reactive.pushList & Reactive.insertList

If you want to insert or push more an entire list instead of an item, use the insertList and pushList methods

todos.insertList(3, [
  { task: 'Write Tests', done: true },
  { task: 'Publish Package', done: false }
])

todos.pushList([
  { task: 'Write Tests', done: true },
  { task: 'Publish Package', done: false }
])

Updating Array nested inside an object

call the reactive with path you want to target and use the update methods

const xyz = reactive({
  foo: {
    bar: {
      bazz: [1, 2, 3]
    }
  }
})

xyz('foo', 'bar', 'bazz').push(4)

Create side effects using effect

effect(() => {
  console.log('count is', count())
})

effect takes a function as argument, this function is executed whenever any reactives that are read inside it are updated.

Create a computed value

Creating a computed value is just as simple as wrapping the expression with a function. So It's basically a helper function that calculates and returns value.

function App() {
  const count = reactive(0)
  const double = () => count() * 2
  return (
    <div>
      <p> count is {count()} </p>
      <p> double is {count() * 2} </p>
      <p> double is {double()} </p>
    </div>
  )
}

Create a memoized value using memo

If a value is calculated as a result of a heavy computation, it is not wise to calculate it everytime like this:

function App() {
  const count = reactive(0)
  const val = () => heavyComputation(count())
  return (
    <div>
      <p> {val()} </p>
      <p> {val()} </p>
      <p> {val()} </p>
    </div>
  )
}

Instead it should be memoized using memo

const val = memo(() => heavyComputation(count()))

With this approach, no matter how many times you read the memoized value - val(), it's value will only be recalculated when any reactive's used for calculating the value isi updated. - count

Lifecycle Hooks

onConnect, onDisconnect

When a component is connected, the function passed to onConnect hook is called. When the component is disconnected, the function passed to onDisconnect hook is called.

function Foo() {
  onConnect(() => {
    console.log('component connected')
  })

  onDisconnect(() => {
    console.log('component disconnected')
  })

  return <p> Hello world </p>
}

You can use these hooks multiple times too:

function Foo() {
  onConnect(() => {
    console.log('component connected 1')
  })

  onConnect(() => {
    console.log('component connected 2')
  })

  return <p> Hello world </p>
}

Custom Hooks

Using effect, onConnect and onDisconnect you can create custom hooks