Validate Module

The std/validate module provides common input validation functions for strings, numbers, and data types.

Import

import { validate } from "std/validate"

String Validators

validate.isEmail(value: string): bool

Returns true if the value is a valid email address.

validate.isEmail("user@example.com") // true
validate.isEmail("not-an-email")     // false

validate.isUrl(value: string): bool

Returns true if the value is a valid URL (has scheme and host).

validate.isUrl("https://example.com") // true
validate.isUrl("not a url")           // false

validate.minLength(value: string, min: int): bool

Returns true if the string length is at least min.

validate.minLength("hello", 3) // true
validate.minLength("hi", 3)    // false

validate.maxLength(value: string, max: int): bool

Returns true if the string length is at most max.

validate.maxLength("hi", 10)    // true
validate.maxLength("hello", 3)  // false

validate.matches(value: string, pattern: string): bool

Returns true if the value matches the given pattern string.

Pattern	Meaning
^prefix	Starts with
suffix$	Ends with
^exact$	Exact match
substring	Contains

validate.matches("hello world", "^hello")   // true
validate.matches("hello world", "world$")   // true
validate.matches("hello world", "lo wo")    // true

validate.isAlpha(value: string): bool

Returns true if the value contains only alphabetic characters.

validate.isAlphanumeric(value: string): bool

Returns true if the value contains only alphanumeric characters.

Type Validators

validate.isRequired(value: any): bool

Returns true if the value is not null and not an empty string.

validate.isRequired("hello") // true
validate.isRequired("")      // false
validate.isRequired(null)    // false

validate.isInt(value: any): bool

Returns true if the value is an integer or a string parseable as an integer.

validate.isFloat(value: any): bool

Returns true if the value is a float or a string parseable as a float.

validate.isString(value: any): bool

Returns true if the value is a string.

validate.isBool(value: any): bool

Returns true if the value is a boolean.

Range Validators

validate.min(value: any, minimum: any): bool

Returns true if the value is greater than or equal to minimum.

validate.min(18, 13)  // true
validate.min(10, 13)  // false

validate.max(value: any, maximum: any): bool

Returns true if the value is less than or equal to maximum.

validate.max(5, 10)   // true
validate.max(15, 10)  // false

Batch Validation

validate.check(results: []bool, messages: []string): map

Validate multiple conditions at once. Returns a map with valid (bool) and errors (array of strings for failed checks).

const result = validate.check(
    [
        validate.isRequired(username),
        validate.minLength(username, 3),
        validate.isEmail(email),
        validate.minLength(password, 8)
    ],
    [
        "Username is required",
        "Username must be at least 3 characters",
        "Invalid email address",
        "Password must be at least 8 characters"
    ]
)

if (!result["valid"]) {
    for (var err of result["errors"]) {
        println(err)
    }
}

Function Reference

Function	Description
validate.isEmail(value)	Check valid email
validate.isUrl(value)	Check valid URL
validate.isRequired(value)	Check not null/empty
validate.minLength(value, min)	Check minimum string length
validate.maxLength(value, max)	Check maximum string length
validate.isInt(value)	Check integer type
validate.isFloat(value)	Check float type
validate.isString(value)	Check string type
validate.isBool(value)	Check boolean type
validate.min(value, minimum)	Check minimum value
validate.max(value, maximum)	Check maximum value
validate.matches(value, pattern)	Check pattern match
validate.isAlpha(value)	Check alphabetic only
validate.isAlphanumeric(value)	Check alphanumeric only
validate.check(results, messages)	Batch validate with error messages

Example: Registration Validation

import { validate } from "std/validate"
import { createServer, Request, Response } from "std/http"
import { json } from "std/json"

const app = createServer()

app.post("/register", function(req: Request, res: Response): Response {
    const body = json.parse(req.body)
    const username = body["username"]
    const email = body["email"]
    const password = body["password"]

    const result = validate.check(
        [
            validate.isRequired(username),
            validate.minLength(username, 3),
            validate.maxLength(username, 20),
            validate.isAlphanumeric(username),
            validate.isEmail(email),
            validate.minLength(password, 8)
        ],
        [
            "Username is required",
            "Username must be at least 3 characters",
            "Username must be at most 20 characters",
            "Username must be alphanumeric",
            "Invalid email address",
            "Password must be at least 8 characters"
        ]
    )

    if (!result["valid"]) {
        return res.status(400).json(json.stringify(result))
    }

    return res.status(201).json('{"message": "User created"}')
})

app.listen(3000)