2020-typeutils.js

/**
 *      This module provides native variable type checking utilities.
 *      It has no external dependencies.
 *      No parsing or coercion is performed.
 *
 *      @module TypeUtils
 */
const validateUUID = require ( 'uuid-validate' );

// The module definition
const TypeUtils = {

    /**
     * Is the value a string?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isString: value => typeof value === 'string',

    /**
     * Is the value a number?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isNumber: value => {

        // BigInt's are not interchangeable with Math.Number
        if ( typeof value === 'bigint' ) {
            return false;
        }

        return !isNaN ( value ) && typeof value === 'number';
    },

    /**
     * Is the value an integer?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isInteger: value => {
        return !TypeUtils.isInfinite ( value ) &&
            TypeUtils.isNumber ( value ) &&
            parseInt ( value, 10 ) === value
            ;
    },

    /**
     * Is the value a floating point number?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isFloat: value => {
        return ( '' + value ).includes ( '.' ) &&
            parseFloat ( value ) === value &&
            !TypeUtils.isInfinite ( value )
            ;
    },

    /**
     * Is the value equal to JavaScript's Infinity?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isInfinite: value => value === Infinity,

    /**
     * Is the value a boolean?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isBoolean: value => [ false, true ].includes ( value ),

    /**
     * Is the value an object?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isObject: value => {
        return typeof value === 'object' &&
            !TypeUtils.isArrayLike ( value ) &&
            !TypeUtils.isNull ( value )
            ;
    },

    /**
     * Is the value an array?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isArray: value => Array.isArray ( value ),

    /**
     * Is the value array-like (Array, Set or Map)?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isArrayLike: value => value instanceof Set || value instanceof Map || Array.isArray ( value ),

    /**
     * Is the value a function?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isFunction: value => typeof value === 'function',

    /**
     * Is the value equal to NULL?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isNull: value => value === null,

    /**
     * Is the value equal to UNDEFINED?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isUndefined: value => value === undefined,

    /**
     * Is the value either NULL or UNDEFINED
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isNullOrUndefined: value => [ null, undefined ].includes ( value ),

    /**
     * Is the value considered empty?
     * (Numbers, Booleans aren't ever considered "empty")
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isEmpty: value => {

        // Null / Undefined
        if ( TypeUtils.isNull ( value ) || TypeUtils.isUndefined ( value ) ) {
            return true;
        }

        // String
        if ( TypeUtils.isString ( value ) && value.length === 0 ) {
            return true;
        }

        // Arrays
        if ( TypeUtils.isArray ( value ) ) {
            return value.length === 0;
        }

        // Sets, Maps
        if ( TypeUtils.isArrayLike ( value ) ) {
            return value.size === 0;
        }

        // Objects
        if ( TypeUtils.isObject ( value ) && Object.keys ( value ).length === 0 ) {
            return true;
        }

        return false;

    },

    /**
     * Is the value a Date?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isDate: value => {

        return (
            !TypeUtils.isNullOrUndefined ( value )
            && value.constructor === Date
            && TypeUtils.isInteger ( value.getTime () )
        );

    },

    /**
     * Is the value a Promise?
     * @return {boolean}
     * @param value Any arbitrary value
     */
    isPromise: value => Boolean ( value && TypeUtils.isFunction ( value.then ) ),

    /**
     * Is the value a valid specific UUID version?
     * @return {boolean}
     * @param value
     * @param version
     */
    isUUID: ( value, version = 4 ) => validateUUID ( value, version ),

    /**
     * Safe wrapper for checking if an object has a property
     * @return {boolean}
     * @param value
     * @param property
     */
    hasProperty: ( value, property ) => {

        if ( !TypeUtils.isObject ( value ) ) {
            return false;
        }

        return Object.prototype.hasOwnProperty.call ( value, property );

    }

};