How do I check if a string is a valid email with is.js?

Use the is.email('test@test.com') function, which validates against a built-in regex pattern. Override it with is.setRegexp() if you need custom email formats.

is.js vs validator.js for validation?

is.js offers a broader range of checks including type, environment, and time validations, while validator.js focuses more on string and format validations. Choose is.js for comprehensive utility or validator.js for lightweight string checks.

How to override regex patterns in is.js?

Use the configuration method is.setRegexp(/newpattern/, 'name') to replace existing regexps, as shown in the README. This allows custom validations but requires manual setup.

Does is.js work with Node.js?

Yes, most functions like type checks and regex validations work in Node.js, but environment detection functions are browser-only and unavailable in Node modules.

How to check multiple conditions with is.js?

Use the 'all' or 'any' interfaces, e.g., is.all.positive([1,2,3]) for all positive numbers, or is.any.url(['http://test.com', 'invalid']) for any valid URL.

Can I use is.js in a React app for form validation?

Yes, is.js can handle validation logic, but for better integration with React state and forms, consider combining it with libraries like Formik or using it for backend validation checks.

Open-Awesome

is.js

MITJavaScript

A comprehensive, dependency-free JavaScript library for type checking, validation, and environment detection.

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9.1k stars618 forks0 contributors

What is is.js?

is.js is a comprehensive JavaScript validation library that provides over 200 functions for type checking, data validation, and environment detection. It solves the problem of inconsistent validation logic by offering a unified API for checking data types, formats, and runtime conditions across different JavaScript environments.

Target Audience

JavaScript developers who need reliable validation utilities for type checking, data format validation, and environment detection in their applications, particularly those working across browser and Node.js environments.

Value Proposition

Developers choose is.js because it's dependency-free, works consistently across AMD, Node.js, and browser environments, and provides an extensive collection of validation functions through a clean, chainable API with 'not', 'all', and 'any' interfaces for flexible condition checking.

Overview

Micro check library

Use Cases

Best For

Validating user input formats like emails, URLs, and phone numbers
Type checking in JavaScript applications to prevent runtime errors
Environment detection for browser-specific functionality
Data validation in forms and API responses
Checking date ranges and time-based conditions
Detecting device types and capabilities for responsive applications

Not Ideal For

TypeScript projects requiring type-safe validation with full IntelliSense support
Server-side Node.js applications where browser environment detection is irrelevant
Frontend frameworks needing integrated validation with state management (e.g., React Hook Form)
Projects requiring highly customizable regex validations beyond the provided static patterns

Pros & Cons

Pros

Comprehensive Validation Coverage

Provides over 200 functions for type checks, regex validations, string operations, arithmetic comparisons, and time-based checks, as detailed in the extensive README.

Flexible Conditional Interfaces

Includes 'not', 'all', and 'any' modifiers for negation, universal, and existential checks, enabling complex logic like is.all.even([2,4,6]).

Dependency-Free and Lightweight

No external dependencies, ensuring minimal footprint and easy integration without additional package overhead.

Cross-Environment Readiness

Works consistently across AMD, Node.js, and browser environments, with most functions available in all contexts.

Cons

Browser-Limited Environment Detection

Environment checks such as is.ie() or is.mobile() are only available in browser environments and not in Node.js modules, reducing utility for server-side apps.

Static Regex Patterns

Regex validations for common formats like emails or credit cards are predefined and may become outdated, requiring manual override with is.setRegexp() for updates.

Non-Modular Bundle

The library is likely monolithic without ES module support or tree-shaking, potentially increasing bundle size for projects using only a subset of functions.

Frequently Asked Questions

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