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Why does the for loop in vue need to add a key?

Why does the for loop in vue need to add a key?

In Vue, it is crucial to give each item in a list loop a unique key. Key helps Vue track changes to list items, thereby improving rendering efficiency and performance. It must be unique and stable and added via the :key attribute in the for loop. If you don't specify a key, Vue will use the index as the default key, which may cause performance issues.

May 02, 2024 pm 08:24 PM
vue
The role of created in vue

The role of created in vue

The created life cycle hook in Vue will be executed when the instance is created. Its functions include: 1. Data initialization, setting data before template rendering; 2. Initiating asynchronous operations to ensure completion before rendering; 3. Configuration elements, adding before rendering Event listener or style class; 4. Set watch listener to monitor data attribute changes.

May 02, 2024 pm 08:21 PM
vue
The role of methods in vue

The role of methods in vue

In Vue.js, the methods option is used to define reusable and independent methods from the rendering template. These methods respond to user interactions through event handlers, which can improve code reusability, independence, ease of testing, and event handling capabilities.

May 02, 2024 pm 08:21 PM
vue
How to implement the calculation of function return value in vue

How to implement the calculation of function return value in vue

There are three methods in Vue to calculate function return values: 1. Use the computed attribute; 2. Use methods; 3. Return the function directly.

May 02, 2024 pm 08:21 PM
vue
How to calculate function return value in vue

How to calculate function return value in vue

Vue function return values ​​can be calculated in three ways: Calculated properties: Define a function that calculates a value based on component data. Its return value will be cached and only recalculated when the dependent data changes. Method: Define a function that recalculates the value each time it is called. Template inline calculation: Use JavaScript expressions to perform calculations directly in the template.

May 02, 2024 pm 08:18 PM
vue
How to write methods in methods in vue

How to write methods in methods in vue

In Vue, the steps for writing methods in the Methods option are as follows: Define the methods object in the JavaScript block of components. Methods are defined using function expressions, using camelCase notation and without parameters. Within the method body, use the this keyword to access the component instance. Use the v-on directive to call a method from a template, specifying the method name as an argument. Methods can be synchronous or asynchronous, with asynchronous methods declared using the async keyword.

May 02, 2024 pm 08:18 PM
vue
The role of router in vue

The role of router in vue

Vue Router is the official routing management library for Vue.js, used to manage page navigation in single-page applications. The main functions include: Managing page navigation: allowing users to switch between pages. URL Management: Synchronize application state with URLs. Component reuse: Reuse Vue components in different pages. State management: stores routing information and data. Guards: Execute custom code such as authentication checks.

Apr 30, 2024 am 06:03 AM
vue
How to introduce js into ts in vue

How to introduce js into ts in vue

Methods to introduce JavaScript into Vue: To introduce external scripts: use <script src="...">. Use <script> blocks: For smaller snippets, code directly using <script>. Use webpack: Install vue-loader and webpack-cli, configure the vue loader, and use import to introduce it in the Vue component.

Apr 30, 2024 am 06:00 AM
vue
The difference between ts and js in vue

The difference between ts and js in vue

In Vue, the difference between TypeScript (TS) and JavaScript (JS) is that TS is a strongly typed language and JS is a weakly typed language. TS needs to be compiled, and JS is interpreted by the browser. TS has type inference, JS must declare types explicitly. TS uses interfaces to define object shapes, and JS uses object literals. TS supports classes, and JS classes are based on prototypes.

Apr 30, 2024 am 05:57 AM
vue
How to use then in vue

How to use then in vue

then is a chained call method in Vue for handling asynchronous operations. It allows you to execute subsequent code when the asynchronous operation completes, receiving two parameters: resolveHandler (handles the value of the resolved Promise) and rejectHandler (handles the reason for the rejected Promise). You can chain calls to execute multiple then calls in sequence, but be sure to handle the rejected Promise case. then is only used for asynchronous operations, synchronous operations should use its return value directly.

Apr 30, 2024 am 05:54 AM
vue
The difference between this and _this in vue

The difference between this and _this in vue

this and _this in Vue point to the same current Vue instance. This helps ensure that the instance is accessed correctly in all situations, especially when using arrow functions. This is generally recommended, but _this can be used when you need to explicitly represent the current instance or integrate with a third-party library.

Apr 30, 2024 am 05:51 AM
vue
What syntax is used to output data to the page in vue

What syntax is used to output data to the page in vue

Data output syntax in Vue includes: v-bind: used to bind data to HTML attributes, the format is v-bind:attribute_name="expression", such as: <h1 v-bind:title="message"></h1 >Interpolation ({{}}): Directly insert expression text, such as: <p>{{ message }}</p> v-text: Set element text content, such as: <p v-text="message"> </p>v-html: Set the HTML content of the element,

Apr 30, 2024 am 05:48 AM
vue
How to use this in vue

How to use this in vue

In Vue.js, the this keyword refers to the current component instance, which is used to access component data, methods, and properties, and is limited to the scope of the component itself.

Apr 30, 2024 am 05:45 AM
vue 作用域
How to write spaces in vue

How to write spaces in vue

In Vue, space processing is divided into ordinary spaces and non-breaking spaces, which can be handled through template interpolation, directives (v-text, v-html, v-pre) and CSS. Among them, ordinary spaces are standard ASCII space characters, and non-newline spaces are in HTML and will not cause line breaks. Spaces can be used in template interpolation to create gaps, and directives can preserve spaces in HTML. CSS white-space controls the handling of spaces within elements, and v-pre prevents Vue from compiling text content to preserve spaces. You need to be careful to avoid too many spaces. Non-breaking spaces may affect the layout. v-pre is only suitable for predefined text.

Apr 30, 2024 am 05:42 AM
css vue

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