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#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
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#format
PHP
Validate Email (RFC-aware)
Use PHP's built-in FILTER_VALIDATE_EMAIL with the FILTER_FLAG_EMAIL_UNICODE flag for IDN domains, plus a length sanity check. Trust this over hand-rolled regex.
@admin
PHP
Validate Uploaded File
A defense-in-depth check for $_FILES uploads: confirms the upload completed, the size is within bounds, the MIME type matches an allow-list (by libmagic, not by extension), and the file landed where PHP expected.
PHP
Safe JSON Decode (no exceptions)
Wrap json_decode so invalid input gives you a clear false rather than a silent null. PHP 7.3+ JSON_THROW_ON_ERROR makes this cleaner — but the wrapper preserves a simple bool API.
Go
Custom Error Type with Fields
Implement the `error` interface (`Error() string`) on your own type to carry structured data. Pair with `errors.As` so callers can extract the fields.
JavaScript
Validate URL
Validates whether a string is a well-formed URL using the native URL constructor, which matches browser parsing behaviour exactly. Optionally restricts to specific protocols (defaults to http and https). No regex maintenance required — if the browser can parse it as a URL, this returns true.
PHP
Validate URL (scheme + host)
Beyond filter_var, also require the URL to have an http(s) scheme and a non-empty host. Rejects "javascript:" and other risky pseudo-schemes commonly seen in stored XSS.
PHP
Validate IP Address (v4 + v6)
Distinguish IPv4 from IPv6, optionally reject private/reserved/loopback ranges. Useful for hardening server-side fetchers against SSRF.
HTML
Form Validation Attributes
Built-in client-side validation: `required`, `pattern`, `minlength`/`maxlength`, `min`/`max`. The browser blocks submission and shows a native error if anything fails. Always validate on the server too.
PHP
Validate Hex Color
Accept #RGB, #RGBA, #RRGGBB, or #RRGGBBAA hex colors (with or without the leading #). Returns the normalized 6/8-digit lowercase form.
JavaScript
Validate Email Address
Validates an email address using a battle-tested regex that covers the vast majority of real-world addresses without being overly strict. For server-side code, pair this with a confirmation email step — client-side regex alone is not a security measure. Returns a boolean for easy conditional use.
PHP
Normalize Phone Number to E.164
A minimal E.164 normalizer for US/CA numbers — strips formatting, prepends "+1" if missing, and validates the digit count. For full international support, reach for giggsey/libphonenumber-for-php.
PHP
Validate Password Strength
Score a password 0–4 (NIST-inspired, not the full zxcvbn algorithm). Encourages length over complexity; flags well-known weak patterns. Use as a UI hint, not a hard barrier.
PHP
Validate Credit Card (Luhn check)
Apply the Luhn checksum algorithm to a credit card number. Strips spaces/dashes first. This validates the format — not whether the card actually exists or has funds.