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.
• 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.
• nodupElems() - Takes the optional valGet and returns Vld. That Vld returns true if there are no duplicate elements in the tgt. If valGet is specified, the value obtained by applying valGet to each element of tgt is referenced.
• eqAllElems() - Takes the optional valGet and returns Vld. That Vld returns true if all the elements of tgt are equal. If valGet is specified, the value obtained by applying valGet to each element of tgt is referenced.
• 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
}