JSPM – @bisham/predicates@0.0.1

Package Exports

@bisham/predicates
@bisham/predicates/dist/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (@bisham/predicates) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

A utility class providing type-safe predicate functions for common value checks.

Installation

npm install @bisham/predicates

Usage

import { Predicates } from '@bisham/predicates';

// Type-safe checks
if (Predicates.isString(value)) {
  // TypeScript knows value is string here
  console.log(value.toUpperCase());
}

Available Methods

Method	Signature	Description
Type Checks
`isString`	`(value: unknown): value is string`	Checks if value is a string
`isEmptyString`	`(value: unknown): value is ""`	Checks if value is an empty string
`isNotEmptyString`	`(value: unknown): value is string`	Checks if value is a non-empty string
`isNumber`	`(value: unknown): value is number`	Checks if value is a number
`isBoolean`	`(value: unknown): value is boolean`	Checks if value is a boolean
`isFunction`	`(func: unknown): func is Function`	Checks if value is a function
`isObject`	`(value: unknown): value is Record<string, unknown>`	Checks if value is an object (not null)
`isDate`	`(value: unknown): value is Date`	Checks if value is a Date instance
Null/Undefined Checks
`isNull`	`(value: unknown): value is null`	Checks if value is `null`
`isUndefined`	`(value: unknown): value is undefined`	Checks if value is `undefined`
`isEmpty`	`(value: unknown): value is null \| undefined`	Checks if value is `null` or `undefined`
`isNotEmpty`	`(value: unknown): value is {}`	Checks if value is neither `null` nor `undefined`
Array Checks
`isEmptyArray`	`(value: unknown): value is []`	Checks if value is an empty array
`isNotEmptyArray`	`(value: unknown): value is Array<unknown>`	Checks if value is a non-empty array
Object Checks
`isEmptyObject`	`(value: unknown): value is Record<string, unknown>`	Checks if value is an object with no properties
Date Checks
`isValidDateString`	`(value: unknown): value is string`	Checks if value is a valid date string
Environment Checks
`isBrowser`	`(): boolean`	Checks if current environment is a browser
`isOnline`	`(): boolean`	Returns online status (browser) or `false` (Node.js)

Examples

import { Predicates } from '@bisham/predicates';

// Type guards with TypeScript narrowing
const value: unknown = "hello";

if (Predicates.isString(value)) {
  // TypeScript knows value is string
  console.log(value.length); // ✅ Works
}

// Check for empty values
if (Predicates.isEmpty(userInput)) {
  console.log("Input is required");
}

// Check arrays
if (Predicates.isNotEmptyArray(items)) {
  // TypeScript knows items is Array<unknown>
  items.forEach(item => console.log(item));
}

// Environment checks
if (Predicates.isBrowser()) {
  console.log("Running in browser");
}

if (Predicates.isOnline()) {
  console.log("User is online");
}