magik-react-hooks

A collection of common (and useful) hooks

Install

npm install --save magik-react-hooks

or

yarn add magik-react-hooks

Docs

Available hooks

• useConstant
• usePrevious
• useRouter (requires react-router) :warning: Deprecated!
• useQueryParams (requires query-string)
• useQueryParam (requires query-string)
• useRouterQueryParams (requires query-string and react-router)
• useRouterQueryParam (requires query-string and react-router)
• useDebounce
• useDebounceCallback
• useRouterDebounceQueryParams
• useModalTrigger

useConstant

Keeps a constant value stable across renders

import useConstant from 'magik-react-hooks/useConstant'

const constant = useConstant(23)
const anotherConstant = useConstant(() => 42)

usePrevious

Injects into the current render the value of its argument during the previous render

import usePrevious from 'magik-react-hooks/usePrevious'

const prev = usePrevious(someProp)
const anotherPrev = usePrevious(someFunc)

useRouter :warning: Deprecated!

Injects React Router context into current component

import useRouter from 'magik-react-hooks/useRouter'

const { history, location } = useRouter()

use:

import { useLocation, useHistory } from 'react-router'

instead.

useQueryParams

Injects in the current component the params set in the query string, optionally transformed with a decoder/encoder

import useQueryParams from 'magik-react-hooks/useQueryParams'

const [params, setParams] = useQueryParams(queryString, setQueryString, encDec, opts)

The queryString parameter is the querystring to parse and to extract params from The setQueryString callback is called whenever there is the need to update the querystring (for instance, because setParams was called)

The opts parameter is an object that is passed as the second parameter to query-string.stringify(), and can be used to control the behaviour of the query-string library. Usually, you want to skip URL encoding, like

// Assuming get_current_querystring and set_current_querystring to be (well) defined
const qs = get_current_querystring()
const setQs = qs => set_current_querystring(qs)
const [params, setParams] = useQueryParams(qs, setQs, encDec, { encode: false })

The encDec param is the encoder and decoder. This param is used when converting data to be written in the query string and the other way round. There are several options for this param

1. A function with the signature (fromQs: any, toQs: any) => any

In this case, the same function is used both for encoding and decoding. In encoding mode, the first parameter is undefined and the second one holds the whole data object to be written in the query string, and the returned value is passed in query-string.stringify(). In decoding mode, the first parameter holds the output of query-string.parse(), while the second one is undefined. In this last case, the return value of the function is returned from the hook as the params entity

2. An object with the signature { encoding: any => any, decoding: any => any }

This is similar to the previous case, except that we have distinct functions for distinct operations and we don't need to discuss about undefined positionals to understand the operating mode.

3. An object with the signature { [prop]: { encoding: any => any, decoding: any => any }}

This case allows to define distinct encoder and decoder functions for arbitrary keys. The logic is always the same except that if you define an encoder/decoder for a given prop, those functions will be invoked with the corresponding prop from the data object, and not with the whole object.

4. An object with the signature { [prop]: (fromQs: any, toQs: any) => any}

This case allows to use the function format on a single key. In encoding mode, the first parameter is undefined and the second one holds the value of prop in the data object to be written to the query string, and the returned value is merged with the other keys and then passed in query-string.stringify(). In decoding mode, the first parameter holds the output of query-string.parse()[prop], while the second one is undefined. In this last case, the return value of the function is merged with the other values and returned from the hook as the params entity

5. A mixture of (2), (3) and (4)

You can also specify a global encoder and key-based decoders, or any combination. Refer to the TestComponent defined in the example.

The library ships with some common encoders and decoders, which are

import {
  qpDate,
  qpInt,
  qpFloat,
  qpBool,
  qpNullable
} from 'magik-react-hooks/qpUtils'

They should be used with pattern (4), like

// Assuming get_current_querystring and set_current_querystring to be (well) defined
const qs = get_current_querystring()
const setQs = qs => set_current_querystring(qs)
const [params, setParams] = useQueryParams(qs, setQs, {
  from: qpDate(),
  to: qpDate()
})

In order to allow for custom configuration of basic props, the library exports encoder/decoder builders, which must be invoked with configuration arguments to return the valid encoder/decoder

The qpDate invocation supports two optional params:

• dateLib: a moment-like date library
• format: the encoding format for dates (ignored if first param is left to default value)

The qpInt invocation supports one (optional) param: the radix (defaults to 10)

The qpFloat invocation does not support any param

The qpBool invocation supports two arguments: the former is the encoding of the boolean value true, the latter is the same for false. Both them are coerced to strings, so pass suitable values.

The qpNullable encoder is a sort of meta-encoder: its invocation requires you to pass another encoder as the first parameter (this can be another qpXXX or a custom encoder), which will be used to encode/decode the value when it is not null, and a string that is used to represent the value null in the querystring (this should be a value that is not part of the data domain)

Feel free to refer to the implementation of those encoders and decoders when you need to write some custom one

useRouterQueryParams

Same as useQueryParams, but it reads from and writes to React Router's location.search, hence the signature becomes:

import useRouterQueryParams from 'magik-react-hooks/useRouterQueryParams'

const [params, setParams] = useRouterQueryParams(encDec, opts)

Obviously, you can use this in a component that is a (deep) child of a Router

useQueryParam

Injects in the current component the a param set in the query string, optionally transformed with a decoder/encoder

import useQueryParam from 'magik-react-hooks/useQueryParam'

const [myParam, setMyParam] = useQueryParam(
  queryString,
  setQueryString,
  paramName,
  defaultValue,
  encDec,
  opts
)

The queryString parameter is the querystring to parse and to extract params from The setQueryString callback is called whenever there is the need to update the querystring (for instance, because setParams was called)

The paramName and defaultValue parameters have a pretty obvious meaning: they are the name of the param to return and the value to return in case the param is not found in the querystring

The opts parameter is an object that is passed as the second parameter to query-string.stringify(), and can be used to control the behaviour of the query-string library. Usually, you want to skip URL encoding, like

// Assuming get_current_querystring and set_current_querystring to be (well) defined
const qs = get_current_querystring()
const setQs = qs => set_current_querystring(qs)
const [myParam, setMyParam] = useQueryParam(
  qs, setQs, paramName, defaultValue, encDec, { encode: false }
)

The encDec param is the encoder and decoder. This param is used when converting data to be written in the query string and the other way round. There are two options for this param

1. A function with the signature (fromQs: any, toQs: any) => any

In this case, the same function is used both for encoding and decoding. In encoding mode, the first parameter is undefined and the second one holds the param to be written in the query string. The returned value is merged in current query params and then passed in query-string.stringify(). In decoding mode, the first parameter holds the output of query-string.parse()[paramName], while the second one is undefined. In this last case, the return value of the function is returned from the hook as the myParam entity. If no param with the given name could be found in the query string, the default value is returned without invoking the decoder.

2. An object with the signature { encoding: any => any, decoding: any => any }

This is similar to the previous case, except that we have distinct functions for distinct operations and we don't need to discuss about undefined positionals to understand the operating mode.

The setMyParam function returned by the hook is used to change the value of the parameter in the query string, and it is expected to be invoked with the next value for the parameter (like native useState without functional updates)

The common encoders and decoders presented in previous section (qpInt, qpFloat and qpDate) are granted to work also with useQueryParam

useRouterQueryParam

Same as useQueryParam, but it reads from and writes to React Router's location.search, hence the signature becomes:

import useRouterQueryParam from 'magik-react-hooks/useRouterQueryParam'

const [params, setParams] = useRouterQueryParam(paramName, defaultValue, encDec, opts)

Obviously, you can use this in a component that is a (deep) child of a Router

useDebounce

Used to debounce a state. It is useful when you have a state that changes quickly and you need to debounce the execution of a side effect which depends on that state. This hook takes as argument the state to debounce and the debounce time (in milliseconds), and returns the debounced value.

import useDebounce from 'magik-react-hooks/useDebounce'

const [state, setState] = useState(0)
const debouncedValue = useDebounce(state, time)

useDebounceCallback

This hook works just like useCallback, but returns a function that calls your callback in a debouced fashion.

import useDebounceCallback from 'magik-react-hooks/useDebounceCallback'

const [state, setState] = useState(0)
const debCallback = useDebounceCallback(fun, delay = 0, [ /* deps of fun */ ])

useRouterDebounceQueryParams

This hook solves one of the major problems in react development: state debouncing. The common case for this is when you have a text input writing a value in the query string, which in turn is used to filter results of a REST API call. In this situation, you need both the real-time updated state (to feed the input) and a debounced state (to avoid repeated and useless API calls). This hooks hence returns a state and its debounced version, plus some helpers to set it immediately and in a debounced way. All control is then up to you

import useRouterDebounceQueryParams from 'magik-react-hooks/useRouterDebounceQueryParams'

const [
  liveState, setLiveState, 
  debouncedState, setDebouncedState
] = useRouterDebounceQueryParams(qpEncoder, options)

setLiveState is immediate, and updates at the same time liveState and debouncedState, while setDebouncedState updates liveState immediately and debouncedState when setDebouncedState calls stop for a while.

You can configure the delay with options.delay, default value is 200ms.

In short, liveState is always the up-to-date state, while debouncedState follows it according to debouncing mechanics. The query string follows the same dynamics of debouncedState. This allows for a better UX when using the browser navigation buttons.

useModalTrigger

This hook aims at easing out modal management. When dealing with lists of objects, one of the possible implementations of the list/detail pattern is to open a modal to read or edit one object selected from the list. This implies that the modal rendering has a hard dependency on the selected item, and that when no item is selected the modal should not be mounted (or otherwise its render method must be carefully written). A naive solution for this situation is the following

const [selectedItem, setSelectedItem] = useState(null)

return (
  <>
    {/* list is rendered here */}
    {selectedItem && (
      <Modal
        isOpen={true}
        toggle={() => setSelectedItem(null)}
        item={selectedItem}
      >
        {/* modal body omitted */}
      </Modal>
    )}
  </>
)

This has the drawback of tying together the open state of the modal and its context. This works, but makes it impossibile to have a closing animation on the modal, as it is unmounted as soon as the selectedItem becomes null.

While using this hook you can separate the context of the modal and the "open" state while exploiting an underline reducer that syncs them when needed

const [{ isOpen, value }, { open, toggle, close, onClosed }] = useModalTrigger()

// This is the way you open the modal "passing" it an item
// The arg of the open function is used to populate the "value" part of the state of the trigger
const onItemSelected = useCallback(item => { open(item) }, [ open ])

return (
  <>
    {/* list is rendered here */}
    {value && (
      <Modal
        isOpen={isOpen}
        toggle={toggle}
        item={value}
        onClosed={onClosed} {/* Note this line */}
      >
        {/* modal body omitted */}
      </Modal>
    )}
  </>
)

By doing so, the modal can be closed before being unmounted, and a proper animation can happen in the meanwhile.

License

MIT © Inmagik s.r.l.