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Glossary |
Glossary |
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This is a glossary of the core terms in Redux Saga.
An effect is a plain JavaScript Object containing some instructions to be executed by the saga middleware.
You create effects using factory functions provided by the redux-saga library. For example you use
call(myfunc, 'arg1', 'arg2')
to instruct the middleware to invoke myfunc('arg1', 'arg2')
and return
the result back to the Generator that yielded the effect
A task is like a process running in background. In a redux-saga based application there can be
multiple tasks running in parallel. You create tasks by using the fork
function
import {fork} from "redux-saga/effects"
function* saga() {
...
const task = yield fork(otherSaga, ...args)
...
}
A Blocking call means that the Saga yielded an Effect and will wait for the outcome of its execution before resuming to the next instruction inside the yielding Generator.
A Non-blocking call means that the Saga will resume immediately after yielding the Effect.
For example
import {call, cancel, join, take, put} from "redux-saga/effects"
function* saga() {
yield take(ACTION) // Blocking: will wait for the action
yield call(ApiFn, ...args) // Blocking: will wait for ApiFn (If ApiFn returns a Promise)
yield call(otherSaga, ...args) // Blocking: will wait for otherSaga to terminate
yield put(...) // Non-Blocking: will dispatch within internal scheduler
const task = yield fork(otherSaga, ...args) // Non-blocking: will not wait for otherSaga
yield cancel(task) // Non-blocking: will resume immediately
// or
yield join(task) // Blocking: will wait for the task to terminate
}
refers to a way of organizing the control flow using two separate Sagas
-
The watcher: will watch for dispatched actions and fork a worker on every action
-
The worker: will handle the action and terminate
example
function* watcher() {
while (true) {
const action = yield take(ACTION)
yield fork(worker, action.payload)
}
}
function* worker(payload) {
// ... do some stuff
}