Top Front End Posts

Uninstall Angular CLI

Angular CLI (Command Line Interface) is a powerful tool for developing and managing Angular applications. However, there may be scenarios where you need to uninstall Angular CLI from your system. Whether it's for a fresh installation or troubleshooting purposes, the process is straightforward. In this article, we will provide you with a step-by-step guide on how to uninstall Angular CLI from your machine, accompanied by examples. Uninstalling Angular CLI: Follow these steps to uninstall Angular CLI from your system: Step 1: Open a Command Prompt or Terminal - On Windows, press `Win + R`, type `cmd`, and press Enter. - On macOS or Linux, open the Terminal application.
Step 2: Check Angular CLI Version Before uninstalling, it's helpful to know which version of Angular CLI is currently installed. You can check this by running the following command:
ng --version
This will display the Angular CLI version along with other related information. Step 3: Uninstall Angular CLI To uninstall Angular CLI, use the following command:
npm uninstall -g @angular/cli
Explanation: - `npm uninstall`: This command removes a package (in this case, the Angular CLI) from your global Node.js modules. - `-g`: This flag specifies that the package should be uninstalled globally. Step 4: Verify Uninstallation After the uninstallation process is complete, it's advisable to verify that Angular CLI has been successfully removed. Run the following command:
ng --version
This should result in a message indicating that the 'ng' command is not recognized, confirming the uninstallation. Example: Let's go through an example of uninstalling Angular CLI on a Windows machine:
# Open Command Prompt #
# Press Win + R, type cmd, and press Enter

# Check Angular CLI version
ng --version

# Uninstall Angular CLI
npm uninstall -g @angular/cli

# Verify uninstallation
ng --version

Conclusion:

Uninstalling Angular CLI is a straightforward process that involves using the npm package manager to remove the global installation. Following the steps outlined in this article, you can easily uninstall Angular CLI from your system, whether for a clean reinstallation or troubleshooting purposes. Always remember to check the version before uninstalling and verify the successful removal of Angular CLI afterward.
This error stems from Angular's strict mode, which ensures variables are properly initialized to avoid potential runtime errors. When you declare a @ViewChild property without initialising it in the constructor, TypeScript gets confused. It doesn't know whether the ViewChild will be assigned later in the component lifecycle, triggering the error.
Solution:
  • Use the non-null assertion operator: Tell TypeScript you trust the property will be assigned later.
@ViewChild('myElement') elementRef!: ElementRef; // Non-null assertion

ngAfterViewInit() {
  // Access elementRef safely
  console.log(this.elementRef.nativeElement);
}



  • Declare as optional: Define the property with | undefined in the type.
@ViewChild('myElement') elementRef: ElementRef | undefined;

ngAfterViewInit() {
  // Use optional chaining to access elementRef safely
  if (this.elementRef) {
    console.log(this.elementRef.nativeElement);
  }
}

  • The best approach depends on your situation:

    • For asynchronous access, the non-null assertion operator works well with careful after-initialization checks.
    • Optional chaining and the | undefined type offer safety for potentially null ViewChild elements.

Phone Number Validation in JavaScript

In today's digital landscape, ensuring the accuracy and validity of user-provided data is crucial, especially for phone numbers. JavaScript, a versatile web scripting language, empowers developers to implement robust phone number validation mechanisms, preventing errors and enhancing user experience. This guide delves into the essential concepts and techniques involved, accompanied by clear and practical code examples:

Understanding Phone Number Formats:

  • US and Canadian Formats:
    • Standard 10-digit format: XXX-XXX-XXXX
    • With spaces: XXX XXX XXXX
    • Without separators: XXXXXXXXXX
    • With country code: +1 XXX-XXX-XXXX
  • India:
    In india phone is 10 digit and starting digits are 6,7,8 and 9.
  • International Formats:
    • Country code variations (e.g., +44 for UK, +86 for China)
    • Flexible length and separator conventions (e.g., spaces, dashes, dots)

JavaScript Regular Expressions for Validation:

  • US and Canada:
const usCanadaRegex = /^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;
India

const indiaRegx = /^[6-9]\d{9}$/;
International (Basic):
const internationalRegex = /^\+[\d]{1,2}\s?[\d]{3,}\s?[\d]{3,}$/;
  • International (Advanced): Utilize libraries like libphonenumber-js for comprehensive international validation and formatting.
    • Code Examples:

      HTML (Form):




      <form id="myForm">
        <label for="phone">Phone Number:</label>
        <input type="text" id="phone" name="phone" required>
        <br>
        <button type="submit">Submit</button>
      </form>
      JavaScript (Validation):
      document.getElementById('myForm').addEventListener('submit', function(event) {  
        event.preventDefault();
        const phone = document.getElementById('phone').value;
      
        const usCanadaRegex = /^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;
        const internationalRegex = /^\+[\d]{1,2}\s?[\d]{3,}\s?[\d]{3,}$/;
      /*  
        or indiaRegx if required
          
       const indiaRegx = /^[6-9]\d{9}$/;
      
      */
      
      
      if (usCanadaRegex.test(phone)) { // Valid US/Canada number alert('Valid US/Canada phone number'); } else if (internationalRegex.test(phone)) { // Basic international validation alert('Valid international phone format (basic)'); } else { alert('Invalid phone number format'); } });
      Key Considerations:
      • Thorough Testing: Test your validation with various phone number formats, including edge cases and invalid inputs.
      • User Experience: Provide clear error messages to guide users in entering valid phone numbers.
      • Advanced Validation: For intricate needs, consider libraries like libphonenumber-js for extended international support, region-specific formats, and more.