JUnit 5 aims to adapt the Java 8 style of coding and to be more robust and flexible than JUnit 4. In this post, JUnit 5 vs JUnit 4, we will focus on some major differences between JUnit 4 and JUnit 5. 1. Different Annotations Most of the annotations in both versions are Read more…
export const NumberContext = React.createContext(); function App() { const [foo, changeFoo] = useState('foo') return ( <NumberContext.Provider value={{ foo, changeFoo }}> <TheButton /> <Display /> </NumberContext.Provider> ); } function TheButton() { const { changeFoo } = useContext(NumberContext) return ( <button onClick={() => changeFoo('bar')}>Click me</button> ); } function Display() { const context Read more…
<div class="box"> <img src="upimg/comm.png"/> </div> <div class="box"> <img src="upimg/comm1.png"/> </div> <div class="box"> <img src="upimg/comm2.png"/> </div> .box{ width: 100%; margin: 20px auto; background: skyblue; position: relative; padding-bottom: 56%; // change this overflow: hidden; } .box>img{ width: 100%; position: absolute; top: 0; left: 0; } Note: padding-bottom attribute: when the value is Read more…
In my project, I jumped to another page before the web request was returned and found that the console reported an error: Warning: Can’t perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all Read more…
First of all, setState has two ways of passing parameters: Pass the new value directly: setState(options) const [state, setState] = useState(0); setState(state + 1); Pass in the callback function: setState(callBack) const [state, setState] = useState(0); setState((prevState) => prevState + 1); // prevState is the state value before the change, // Read more…
SUBSTRING_INDEX(str, delim, count) str: the string to be split. delim: the delimiter. count: the position of the delimiter. A positive number means extract from left to right, a negative number means extract from right to left. For example: SELECT SUBSTRING_INDEX('100-200-300-400', '-', 1); — output: '100' SELECT SUBSTRING_INDEX('100-200-300-400', '-', 2); — Read more…
When using mybatis as a persistence layer, insert, update, delete, sql statements do not return the primary key of the record being operated on by default, but rather the number of records being operated on. When we want to get the primary key automatically generated for the inserted data, we Read more…
The purpose of a sticky footer is that it “sticks” to the bottom of the browser window. But not always, if there is enough content on the page to push the footer lower, it still does that. But if the content on the page is short, a sticky footer will Read more…
When Prettier is used in conjunction with ESLint, ESlint detects the crlf and cr differences between the code runtime and the project creator to the point where all ends of lines errors are reported. Reason For historical reasons, windows and linux have different line feeds for text files. Windows uses Read more…
Last time, I deployed a React.js project on a server. But I found the router doesn’t work. I click the menu to other child pages. It always returns a 404 page. I did some search and found the reason. When I try to get a page by url, nginx would Read more…