React beginner, ask for help how to understand this code?

< H1 > question 1 < / H1 >

what is the difference between the following two pieces of code, and why one uses ({}) and the other does not use

toggleTodo = id => ({
    type: "TOGGLE_TODO",
    id
});

toggleToChange = (id)=> {
    return {
        type: "TOGGLE_TO_CHANGE",
        id
    }
};

< H1 > question 2 < / H1 >

this.setState({
            showPageGroup: showPageGroup,
            showPageNumber: showPageNumber,
            ellipsisNumber: ellipsisNumber,
            endGetIndex: endGetIndex,
            arrowShow: arrowShow,
            userKeyValue: userKeyValue
        })

how does this setState, optimize merging?

Es6 redux react.js

Apr.30,2021

there is no difference between the two pieces of code, both of which define a method that returns an object. The difference lies in the understanding of the arrow function. If the arrow function needs to execute more than one statement, it needs to be wrapped in curly braces. However, curly braces will be considered a literal amount of an object, which will conflict. So when you need to return the literal amount of the object directly, you can enclose it with (), or you can display the return in {}.

this.setState({
            showPageGroup,
            showPageNumber,
            ellipsisNumber,
            endGetIndex,
            arrowShow,
            userKeyValue
        })

Previous: Python3 crawler

Next: The method of transforming python2.7 list into tuples

Redux in react
reducer in redux performs a minus one operation export default (state = initialState, action) => { const {total} = state switch(action.type){ case ActionTypes.ADD: return {...state, total: total + 1} case ActionTypes.SUBT...

Es6 redux react.js

Mar.31,2021
For beginners, why the dispatch in the first paragraph of the code is available and the dispatch in the second paragraph is undefined
first paragraph import React from react import { connect } from react-redux import { addToCart } from .. actions cart-actions let AddTodo = ({ dispatch }) => { let input = ; return ( <div> <...

Es6 redux react.js

Apr.11,2021
Beginner redux, report error Cannot read property 'map' of undefined
import React from react ; import DifferentLabels from . DifferentLabels const DifferentLabelsDiv = ({ todos, toggleTodo }) => ( <div> {todos.map(todo => <DifferentLabels key={todo.id} ...

Es6 redux react.js

Apr.26,2021

MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b32a8c-2b195.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b32a8c-2b195.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
Need Help?