Deno is_x module

This module provides some basic utilities for creating or utilizing type-guarded validation.

Requirement

• Deno v1.14.0+

Usage

The validation in this module is specifically the following Vld type function.

Types

• Vld - A functional type that takes tgt and returns a boolean. If tgt is valid, return true.
• TgVld - A functional type that takes tgt and returns a boolean. If tgt is valid, return true to perform typeguard.
• TgtType - The type of tgt in Vld.
• OkType - The type of type guard for tgt in TgVld, or the type of tgt in Vld.

Functions

• isAny() - A Vld that always returns true.
• isNever() - A TgVld that always returns false.
• isString() - A TgVld that returns true if the tgt is a string.
• isNumber() - A TgVld that returns true if the tgt is a number.
• isInt() - A TgVld that returns true if the tgt is an integer.
• isNonnegInt() - A TgVld that returns true if the tgt is a non-negative integer.
• isBigInt() - A TgVld that returns true if the tgt is a bigint.
• isBoolean() - A TgVld that returns true if the tgt is a boolean.
• isSymbol() - A TgVld that returns true if the tgt is a symbol.
• isNull() - A TgVld that returns true if the tgt is a null.
• isUndefined() - A TgVld that returns true if the tgt is a undefined.
• nodupElems() - A Vld that returns true if there are no duplicate elements in the tgt.
• eq() - Takes base and returns TgVld. That TgVld returns true if tgt is equal to base.
• gt() - Takes base and returns Vld. That Vld returns true if tgt is greater than base.
• lt() - Takes base and returns Vld. That Vld returns true if tgt is less than base.
• ge() - Takes base and returns Vld. That Vld returns true if tgt is greater than or equal to base.
• le() - Takes base and returns Vld. That Vld returns true if tgt is less than or equal to base.
• len() - Takes vld and returns TgVld. That TgVld returns true if the value of the length property of tgt is valid for vld.
• array() - Takes elemVld and the optional lenVld and returns TgVld. That TgVld returns true if tgt is a plain array, all elements are valid for elemVld, and the value of the length property is valid for lenVld.
• tuple() - Takes elemVlds and returns TgVld. That TgVld returns true if tgt is a plain array and each element is valid for each element of elemVlds.
• assoc() - Takes elemVld and returns TgVld. That TgVld returns true if tgt is a plain object and the values of all the properties it owns are valid for elemVld.
• dict() - Takes elemVld and returns TgVld. That TgVld returns true if tgt is a plain object, the keys of all the properties it owns are strings, and the values of those properties are valid for elemVld.
• album() - Takes elemVld and returns TgVld. That TgVld returns true if tgt is a plain object, the keys of all the properties it owns are symbols, and the values of those properties are valid for elemVld.
• interf() - Takes vldSchema and the optional optionalKeys and returns TgVld. That TgVld returns true if tgt is a plain object, and each property it owns is valid for each property owned by vldSchema. Also, for a property that has a key in optionalKeys, it is valid even if the key does not exist or the value is undefined.
• struct() - Takes vldSchema and the optional optionalKeys and returns TgVld. That TgVld returns true if tgt is a plain object, and each property it owns is valid for each property owned by vldSchema, and it owns only properties owned by vldSchema. Also, for a property that has a key in optionalKeys, it is valid even if the key does not exist or the value is undefined.
• extend() - Takes vlds and returns TgVld. That TgVld returns true if tgt is valid for all elements of vlds.
• union() - Takes vlds and returns TgVld. That TgVld returns true if tgt is valid for any element of vlds.
• lazy() - Takes vldGet and args and returns TgVld. That TgVld returns true if tgt is valid for the return value of passing all the elements of args to vldGet.

Examples

Basic:

import { isString, eq, tuple, struct, union }
from 'https://deno.land/x/is_x/mod.ts'

const isResult = union(
    struct({
        kind: eq('ok'),
        data: tuple(isString, isString)
    }),
    struct({
        kind: eq('ng'),
        message: isString
    }, ['message'])
)

const tgt = JSON.parse('{ "kind": "ok", "data": ["a", "b"] }')
if (isResult(tgt)) {
    // Guard the type of tgt
}

Extend:

import { isString, extend }
from 'https://deno.land/x/is_x/mod.ts'

function isURLFmt(tgt: string) {
    // ...
    return true
}
const isURL = extend(isString, isURLFmt)

const tgt = JSON.parse('"https://deno.land/x/is_x"')
if (isURL(tgt)) {
    // Guard the type of tgt
}

Recursive:

import { TgVld, struct, lazy }
from 'https://deno.land/x/is_x/mod.ts'

type LoopNest = { a?: LoopNest }
function loopNest(): TgVld<unknown, LoopNest> {
    return struct({
        a: lazy(loopNest)
    }, ['a'])
}
const isLoopNest = loopNest()

const tgt = JSON.parse('{ "a": { "a": {} } }')
if (isLoopNest(tgt)) {
    // Guard the type of tgt
}