Welcome to our comprehensive guide on ng lint! In this lesson, we will explore Angular's powerful linting tool and learn how it can help you write cleaner, more efficient code.
ng lint? šng lint is a tool that helps you maintain the quality of your Angular code by enforcing coding standards, detecting potential issues, and ensuring consistency across your project. It is an essential tool for every Angular developer and is integrated into the Angular CLI.
ng lint š”To use ng lint, you first need to have Angular CLI installed on your machine. If you haven't installed it yet, you can do so by following the instructions here.
Once you have Angular CLI, you can install ng lint by running the following command in your project directory:
npm install --save-dev @angular-builders/webpack-ng-builders @angular-eslint/builder @angular-eslint/eslint-plugin-template @angular-eslint/eslint-plugin-componentng lint šAfter installing ng lint, you need to configure it to work with your Angular project. To do this, create a new file named .eslintrc.json in the root of your project directory and add the following configuration:
{
"extends": ["@angular-eslint/schema/precommit", "@angular-eslint/schema/style"],
"rules": {
"quotes": [2, "double"],
"semi": [2, "always"],
"indent": [2, 2],
"comma-dangle": [2, "always-multiline"],
"no-unused-vars": [2, { "args": "none", "varsIgnorePattern": "^_" }],
"no-empty": [2, { "allowEmptyCatch": true }]
}
}ng lint š”To run ng lint on your project, use the following command:
ng lintThis command will check your entire project for linting issues and display them in the console.
If you encounter linting issues, you can automatically fix them by running:
ng lint --fixTo have ng lint run automatically whenever you save a file, you can use the Angular CLI's watch command:
ng watch --configuration=lintNow let's see ng lint in action with some examples! š
Create a new Angular component with the following code:
import { Component } from '@angular/core';
@Component({
selector: 'app-example',
template: `
<h1>Hello, World!</h1>
`
})
export class ExampleComponent {
}If you run ng lint on this component, you will see the following output:
ā src/app/example/example.component.ts (2:20)
Template strings must have at least one expression. (template-curly-no-empty)
š Note: Add an expression to the template string to fix the linting issue.
ā src/app/example/example.component.ts (4:1)
Class 'ExampleComponent' incorrectly extends built-ins. (no-implicit-builtins)
š Note: Replace 'ExampleComponent' with 'ExampleComponent' to fix the linting issue.
Fix the issues by modifying the code as follows:
import { Component } from '@angular/core';
@Component({
selector: 'app-example',
template: `<h1>{{ message }}</h1>`,
})
export class ExampleComponent {
message = 'Hello, World!';
}Now, if you run ng lint again, you will see that the component passes the linting checks.
Create a new Angular service with the following code:
import { Injectable } from '@angular/core';
@Injectable({
providedIn: 'root'
})
export class ExampleService {
getData() {
return 'Example Data';
}
}If you run ng lint on this service, you will see the following output:
ā src/app/example.service.ts (3:24)
Class 'ExampleService' incorrectly extends built-ins. (no-implicit-builtins)
š Note: Replace 'ExampleService' with 'ExampleService' to fix the linting issue.
Fix the issue by modifying the code as follows:
import { Injectable } from '@angular/core';
@Injectable({
providedIn: 'root'
})
export class ExampleService {
getData() {
return 'Example Data';
}
}Now, if you run ng lint again, you will see that the service passes the linting checks.
Which command runs `ng lint` on the entire project and displays linting issues?
That's it for our comprehensive guide on ng lint! You now have a good understanding of what ng lint is, how to install and configure it, and how to use it to maintain the quality of your Angular code.
Happy coding, and remember to keep learning! š”š