Full Stack JavaScript Form Validation with JavaScript Knowledge Assessment, Exams of Programming Languages

Download Full Stack JavaScript Form Validation with JavaScript Knowledge Assessment and more Exams Programming Languages in PDF only on Docsity! Full Stack JavaScript Form Validation with JavaScript Knowledge Assessment Q & S 2024 1. When validating an email address using JavaScript, what kind of pattern is commonly used? a) URL pattern b) Regular expression c) Loop iteration d) JSON format Answer: b) Regular expression Rationale: Regular expressions (regex) are commonly used for pattern matching and validation, including email validation. 2. Which built-in JavaScript method is commonly used to check if a string contains a particular substring during validation? a) `parseInt()` b) `substr()` c) `includes()` d) `validate()` Answer: c) `includes()` Rationale: The `includes()` method determines whether one string contains another string, returning `true` or `false`. 7. ```javascript const phonePattern = /^[0-9]{10}$/; if (!phonePattern._________(phoneInput.value)) { alert("Invalid phone number"); } ``` Answer: test Rationale: The `test` method is used to check if a string matches the regular expression. 8. For better readability and maintainability, form validation logic can be abstracted into ___________. Answer: functions Rationale: Functions encapsulate logic for reuse and clarity. 9. ```javascript function validatePassword(password) { const minLength = 8; if (password.length < minLength) { __________("Password is too short"); return false; } return true; } ``` Answer: alert Rationale: Alert the user if the password is shorter than the required minimum length. 10. ```javascript document.querySelector('form').addEventListener('_______', function(event) { if (!validateForm()) { event.preventDefault(); } }); ``` Answer: submit Rationale: Attach the submit event to execute validation before form submission. True/False Questions 11. True or False: JavaScript form validation can completely replace server-side validation. Answer: False Rationale: Client-side validation enhances user experience but should not replace server-side validation which is essential for security. 12. True or False: The `setCustomValidity()` method can be used to display custom error messages for forms validated with JavaScript. Answer: True Rationale: `setCustomValidity()` sets a custom validity message for the input element. 13. True or False: Using HTML5 constraint validation doesn't require any JavaScript for basic validation needs. Answer: True Rationale: HTML5 provides built-in validation constraints like `required`, `minlength`, `type`, etc. 14. True or False: The `addEventListener` method can be used to attach form validation to multiple events simultaneously. ii. checkEmpty() iii. isNull() iv. validateEmpty() Correct Answer: i. isEmpty() Rationale: The isEmpty() method is often used to validate if a field is empty in JavaScript form validation. Fill-in-the-Blank: a. To ensure that an email address is in the correct format, the regular expression _ can be used in JavaScript form validation. Correct Answer: /\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b/i Rationale: This regular expression validates the format of an email address by checking for typical email patterns. True/False: a. True or False: When performing form validation in JavaScript, it is essential to use client-side validation only. Correct Answer: False Rationale: While client-side validation is common, server-side validation is crucial for security and data integrity. Multiple Choice: a. Which event is commonly used to trigger form validation in JavaScript? i. onSubmit ii. onClick iii. validateForm iv. onValidate Correct Answer: i. onSubmit Rationale: The onSubmit event is typically used to trigger form validation when a form is submitted. Fill-in-the-Blank: a. The _ method in JavaScript can be used to dynamically add validation rules to form elements. Correct Answer: setCustomValidity() Rationale: This method allows developers to add custom validation rules to form fields in JavaScript. True/False: a. True or False: JavaScript form validation can help improve user experience by providing instant feedback on input errors. Correct Answer: True Rationale: Instant feedback through form validation can enhance user experience by guiding users to correct input errors promptly. Multiple Choice: a. Which attribute is commonly used in HTML forms to link a form field with its corresponding validation message? i. validate ii. data-validation iii. aria-describedby iv. error-message Correct Answer: iii. aria-describedby Rationale: The aria-describedby attribute is often used to associate form fields with their validation messages for accessibility. Rationale: Regular expressions are powerful tools in JavaScript form validation for defining and matching complex patterns. Multiple Choice: a. Which attribute can be used in HTML form elements to specify a required field for validation? i. required ii. validate iii. mandatory iv. validate-required Correct Answer: i. required Rationale: The required attribute is used in HTML form elements to mark a field as required for validation. Fill-in-the-Blank: a. The _ method in JavaScript can be used to prevent form submission if validation conditions are not met. Correct Answer: preventDefault() Rationale: The preventDefault() method allows developers to stop form submission if validation criteria are not satisfied. True/False: a. True or False: JavaScript form validation can help reduce the number of server requests by catching errors before submitting the form. Correct Answer: True Rationale: By catching errors on the client side, JavaScript form validation can reduce unnecessary server requests and improve overall efficiency in form handling. 1. Multiple Choice: What is the purpose of using regular expressions in form validation? a) To format text b) To secure the form c) To check the form data against specific patterns d) To style the form Answer: c) To check the form data against specific patterns Rationale: Regular expressions are used in form validation to ensure that the input matches a certain format or pattern, such as email addresses or phone numbers. 2. True/False: The `onsubmit` event triggers the validation process before sending the form data to the server. Answer: True Rationale: The `onsubmit` event is commonly used to trigger form validation in JavaScript, ensuring that the data is checked before it is sent to the server. 3. Fill-in-the-Blank: The _______ method is used to prevent the form from being submitted if the validation fails. Answer: `preventDefault()` Rationale: The `preventDefault()` method stops the default action of an element from happening. In the context of forms, it prevents the form from submitting when the validation does not pass. 4. Multiple Choice: Which HTML5 attribute automatically validates the input of an email field? a) `type="email"` b) `validate="email"` c) `format="email"` d) `pattern="email"` Answer: a) `type="email"` Rationale: The `type="email"` attribute in an input field is used by browsers to validate the entered value as an email address. 5. True/False: Custom error messages for form validation can be set using the `setCustomValidity()` method. Answer: True 12. Fill-in-the-Blank: The JavaScript event `_______` is ideal for validating each field right before submission. Answer: `submit` Rationale: The `submit` event occurs on a form just before it is submitted, making it a suitable time to perform final validation checks. 13. Multiple Choice: Which method is used to manually trigger the validation of a specific form element? a) `validate()` b) `checkValidity()` c) `reportValidity()` d) `confirmValidity()` Answer: b) `checkValidity()` Rationale: The `checkValidity()` method is used to check if an element's value satisfies its constraints and is used for manual validation. 14. True/False: Inline JavaScript within form event attributes is the recommended way to handle form validation. Answer: False Rationale: Inline JavaScript is generally discouraged due to concerns with maintainability and security. External scripts are preferred for handling form validation. 15. Fill-in-the-Blank: For a more accessible user experience, it's important to use _______ to describe errors related to form validation. Answer: `aria-live` Rationale: The `aria-live` attribute is used to indicate that an element will update dynamically, and assistive technologies will announce the updates, which is useful for conveying validation errors to users who rely on screen readers.