import clone from 'just-clone';
-import Constants from './Constants';
-import { WebSocketCloseEventStatusString } from '../types/WebSocket';
+import { Constants } from './Constants';
+import { WebSocketCloseEventStatusString } from '../types';
-export default class Utils {
+export class Utils {
private constructor() {
// This is intentional
}
- public static logPrefix(prefixString = ''): string {
+ public static logPrefix = (prefixString = ''): string => {
return `${new Date().toLocaleString()}${prefixString}`;
- }
+ };
public static generateUUID(): string {
return crypto.randomUUID();
return result;
}
- public static getRandomFloat(max = Number.MAX_VALUE, min = 0, negative = false): number {
- if (max < min || max < 0 || min < 0) {
+ public static getRandomFloat(max = Number.MAX_VALUE, min = 0): number {
+ if (max < min) {
+ throw new RangeError('Invalid interval');
+ }
+ if (max - min === Infinity) {
throw new RangeError('Invalid interval');
}
- const randomPositiveFloat = crypto.randomBytes(4).readUInt32LE() / 0xffffffff;
- const sign = negative && randomPositiveFloat < 0.5 ? -1 : 1;
- return sign * (randomPositiveFloat * (max - min) + min);
+ return (crypto.randomBytes(4).readUInt32LE() / 0xffffffff) * (max - min) + min;
}
public static getRandomInteger(max = Constants.MAX_RANDOM_INTEGER, min = 0): number {
return clone<T>(object);
}
- public static isIterable<T extends Iterable<T>>(obj: T): boolean {
+ public static hasOwnProp(object: unknown, property: PropertyKey): boolean {
+ return Utils.isObject(object) && Object.hasOwn(object as object, property);
+ }
+
+ public static isCFEnvironment(): boolean {
+ return !Utils.isNullOrUndefined(process.env.VCAP_APPLICATION);
+ }
+
+ public static isIterable<T>(obj: T): boolean {
return !Utils.isNullOrUndefined(obj) ? typeof obj[Symbol.iterator] === 'function' : false;
}
}
public static isEmptyString(value: unknown): boolean {
- return Utils.isString(value) && (value as string).trim().length === 0;
+ return (
+ Utils.isNullOrUndefined(value) ||
+ (Utils.isString(value) && (value as string).trim().length === 0)
+ );
+ }
+
+ public static isNotEmptyString(value: unknown): boolean {
+ return Utils.isString(value) && (value as string).trim().length > 0;
}
public static isUndefined(value: unknown): boolean {
public static isNullOrUndefined(value: unknown): boolean {
// eslint-disable-next-line eqeqeq, no-eq-null
- return value == null ? true : false;
+ return value == null;
}
- public static isEmptyArray(object: unknown | unknown[]): boolean {
- if (!Array.isArray(object)) {
- return true;
- }
- if (object.length > 0) {
- return false;
- }
- return true;
+ public static isEmptyArray(object: unknown): boolean {
+ return Array.isArray(object) && object.length === 0;
+ }
+
+ public static isNotEmptyArray(object: unknown): boolean {
+ return Array.isArray(object) && object.length > 0;
}
public static isEmptyObject(obj: object): boolean {
* @param retryNumber - the number of retries that have already been attempted
* @returns delay in milliseconds
*/
- public static exponentialDelay(retryNumber = 0): number {
+ public static exponentialDelay(retryNumber = 0, maxDelayRatio = 0.2): number {
const delay = Math.pow(2, retryNumber) * 100;
- const randomSum = delay * 0.2 * Utils.secureRandom(); // 0-20% of the delay
+ const randomSum = delay * maxDelayRatio * Utils.secureRandom(); // 0-20% of the delay
return delay + randomSum;
}
}
return '(Unknown)';
}
+
+ public static median(dataSet: number[]): number {
+ if (Utils.isEmptyArray(dataSet)) {
+ return 0;
+ }
+ if (Array.isArray(dataSet) === true && dataSet.length === 1) {
+ return dataSet[0];
+ }
+ const sortedDataSet = dataSet.slice().sort((a, b) => a - b);
+ return (
+ (sortedDataSet[(sortedDataSet.length - 1) >> 1] + sortedDataSet[sortedDataSet.length >> 1]) /
+ 2
+ );
+ }
+
+ // TODO: use order statistics tree https://en.wikipedia.org/wiki/Order_statistic_tree
+ public static percentile(dataSet: number[], percentile: number): number {
+ if (percentile < 0 && percentile > 100) {
+ throw new RangeError('Percentile is not between 0 and 100');
+ }
+ if (Utils.isEmptyArray(dataSet)) {
+ return 0;
+ }
+ const sortedDataSet = dataSet.slice().sort((a, b) => a - b);
+ if (percentile === 0 || sortedDataSet.length === 1) {
+ return sortedDataSet[0];
+ }
+ if (percentile === 100) {
+ return sortedDataSet[sortedDataSet.length - 1];
+ }
+ const percentileIndexBase = (percentile / 100) * (sortedDataSet.length - 1);
+ const percentileIndexInteger = Math.floor(percentileIndexBase);
+ if (!Utils.isNullOrUndefined(sortedDataSet[percentileIndexInteger + 1])) {
+ return (
+ sortedDataSet[percentileIndexInteger] +
+ (percentileIndexBase - percentileIndexInteger) *
+ (sortedDataSet[percentileIndexInteger + 1] - sortedDataSet[percentileIndexInteger])
+ );
+ }
+ return sortedDataSet[percentileIndexInteger];
+ }
+
+ public static stdDeviation(dataSet: number[]): number {
+ let totalDataSet = 0;
+ for (const data of dataSet) {
+ totalDataSet += data;
+ }
+ const dataSetMean = totalDataSet / dataSet.length;
+ let totalGeometricDeviation = 0;
+ for (const data of dataSet) {
+ const deviation = data - dataSetMean;
+ totalGeometricDeviation += deviation * deviation;
+ }
+ return Math.sqrt(totalGeometricDeviation / dataSet.length);
+ }
}