code sky

 An error is reported when using webpack-dev-server to build a development server, and the error message is as follows:[webpack-cli] TypeError: cli.isMultipleCompiler is not a function.

 Global routing front guard (beforeEach) This function is used the most. Its function is to perform permission-related verification before routing jumps. This function contains three parameters: to: the object of the target route that is about to enter; from: the route that the current route is leaving; next: confirm the release. It can be used to log in and register, to determine whether there is a token before logging in, and release if it exists. , if it does not exist, it will not be released. The post routing guard (afterEach), its role is to trigger after the routing jump.

 The creation and mounting of components that use the cache <keep-alive> at the beginning will be executed the same as the components that do not use the cache, but the components that use the cache will not be destroyed when switching components, and the activated function will be triggered when switching back again. , the deactivated function will be triggered when switching, and components that do not use the cache cannot use the activated function. Simply put, the activated function is a hook function after the page is activated, which is triggered as soon as the page is entered. So when we use component caching, if we want to send a request every time we switch, we need to write the request function in activated, and in created or mounted, it will only work when the component is loaded for the first time.

 When we switch from one component to another, the routing component that has not been displayed remains mounted and not destroyed. When we switch back, the previous data is still maintained, for example, entering data in a text box, Then switch to another page, and then switch to the previous text box interface, the data of the text box is still saved. The web page experience will be better.

 The role of props configuration in routing is to make it easier for routing components to receive parameters.It is very convenient to use. The following describes three ways to use props to pass and receive parameters.

 The main feature of SPA single page is that a layer of front-end routing is added on the basis of the separation of front-end and back-end. That is, the front end maintains a set of routing rules. The user clicks the routing link on the page, which causes the Hash value in the URL address bar to change. The front-end routing monitors the change of the Hash address, and the front-end routing renders the component corresponding to the current Hash address to the browser. Vue-router is the routing solution officially given by Vue. It can only be used in conjunction with the vue project, and can easily manage the switching of components in the SPA project. For VueRouter, routing is the decision-making process of selecting a component for rendering based on a request path.