How to use typescript for type checking in Vue

Vue is a popular front-end framework that uses template syntax to render applications and provides rich components and life cycle hooks. However, Vue was originally written in JavaScript, and JavaScript is a weakly typed language, which means that when developing large applications, it is easy to make type errors. To solve this problem, Vue can use TypeScript for type checking.

TypeScript is a superset of JavaScript that adds features such as strong type support, classes and interfaces, and uses tools to perform type checking. TypeScript provides better type safety for Vue applications, helping developers find and avoid type errors when writing code. In this article, we will discuss how to use TypeScript for type checking in Vue.

1. Install Vue and TypeScript

First, install Vue and TypeScript. Vue and TypeScript can be installed directly using the Vue CLI or npm, or using a CDN link to install Vue. After the installation is complete, we need to use TypeScript in the Vue application.

2. Configuring TypeScript

In order for Vue to recognize TypeScript, we need to add a TypeScript configuration file to the Vue application. TypeScript can be configured by creating a tsconfig.json file. In this file, some configuration options need to be set, for example:

{
  "compilerOptions": {
    "target": "es5",
    "module": "es2015",
    "strict": true,
    "esModuleInterop": true,
    "noImplicitAny": true,
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "allowSyntheticDefaultImports": true
  },
  "include": [
    "src/**/*"
  ],
  "exclude": [
    "node_modules"
  ]
}

In the above configuration, we set the compilation option to es5, use the es2015 modular specification, and turn on strict type mode and implicit arbitrary type checking , parsing node module. In addition, the include configuration option is used to specify the source files that need to be compiled, and the exclude option excludes files or folders that do not need to be compiled.

3. Using TypeScript in Components

Now that we have configured Vue and TypeScript, we need to ensure that TypeScript types are used correctly in the component. In Vue, you can specify the type of a component's properties and methods by writing a TypeScript interface for the component. For example:

<template>
  <div>
    <h1>{{ title }}</h1>
  </div>
</template>

<script lang="ts">
import { Component, Vue } from 'vue';

interface HelloWorldProps {
  title: string;
}

@Component
export default class HelloWorld extends Vue {
  title!: HelloWorldProps['title'];
}
</script>

In the above code, we created an interface named HelloWorldProps for the HelloWorld component. This interface defines the type of the title attribute of the component as a string. Then, in the component, we use TypeScript's class syntax and inherit the Vue class to write the component. The attribute title in the class uses an exclamation point suffix, which means it is a non-empty attribute.

4. Using Decorators

In Vue, you can also use decorators to write TypeScript code. Vue class components is a very useful library that provides a set of decorators to help us write TypeScript code.

First, you need to use npm to install Vue Class Component and Vue Property Decorator:

npm install vue-class-component vue-property-decorator --save-dev

Then, you can use decorators in the component to define the types of properties and methods, for example:

<template>
  <div>
    <h1>{{ title }}</h1>
  </div>
</template>

<script lang="ts">
import { Component, Vue } from 'vue-property-decorator';

@Component({
  props: {
    title: {
      type: String,
      required: true,
    },
  },
})
export default class HelloWorld extends Vue {
  get titleUpper(): string {
    return this.title.toUpperCase();
  }
}
</script>

In the above code, we use the @Component decorator in the Vue Property Decorator library to define the properties of the component, including the type of the title attribute. In the class, we define a getter method titleUpper to return the uppercase title attribute value.

5. Summary

This article introduces how to use TypeScript for type checking in Vue, including configuring TypeScript and using TypeScript interfaces and decorators in components. By using TypeScript, we can help Vue applications achieve type safety, avoid type errors and bugs during the development process, and improve the maintainability and scalability of the application.

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