Intermediate LevelHTML & Semantic Web
How do you enforce custom pattern validation using regular expressions on HTML inputs?
❓ Interview Prompt: Explain pattern attribute on input elements, inline regex validation, title attribute for helper text, and :invalid CSS.
The 'pattern' attribute specifies a JavaScript Regular Expression that the input's value must match before form submission.
Helper Text:
When validation fails, browsers display the text provided in the 'title' attribute inside the native error bubble!
Code Implementation Example
html
<form>
<label for="credit-card">Credit Card (16 digits):</label>
<input
type="text"
id="credit-card"
name="card"
pattern="[0-9]{16}"
title="Please enter a 16-digit credit card number"
required
>
<button type="submit">Pay</button>
</form>💡Regex pattern validation on credit card input with custom error title text.
🎯 Interview Key Takeaway
Use input pattern="regex" with title="helper text" to enforce custom format validation natively.
#pattern attribute#Regex#Form Validation#Intermediate
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