Avoid strictNullChecks errors

Author: fknop

package.json

@@ -1,6 +1,6 @@
 {
   "name": "angular-pipes",
-  "version": "6.1.1",
+  "version": "6.1.2",
   "description": "Angular pipes library",
   "main": "src/index.js",
   "jsnext:main": "esm/index.js",

src/string/with.pipe.ts

@@ -4,7 +4,7 @@ import {isString, isNull} from '../utils/utils';
 @Pipe({name: 'with'})
 export class WithPipe implements PipeTransform {
 
-  transform(input: string, start: string = null, ends: string = null, csensitive: boolean = false): any {
+  transform(input: string, start: string|null = null, ends: string|null = null, csensitive: boolean = false): any {
 
     if (!isString(input) || (isNull(start) && isNull(ends)) || (start == '') || (ends == '')) {
       return input;

src/utils/utils.ts

@@ -1,21 +1,21 @@
 export type CollectionPredicate = (item?: any, index?: number, collection?: any[]) => boolean;
 
-export function isUndefined (value: any): boolean {
+export function isUndefined (value: any): value is undefined {
 
   return typeof value === 'undefined';
 }
 
-export function isNull (value: any): boolean {
+export function isNull (value: any): value is null {
 
   return value === null;
 }
 
-export function isNumber (value: any): boolean {
+export function isNumber (value: any): value is number {
 
   return typeof value === 'number';
 }
 
-export function isNumberFinite (value: any): boolean {
+export function isNumberFinite (value: any): value is number {
 
   return isNumber(value) && isFinite(value);
 }
@@ -33,11 +33,11 @@ export function isInteger (value: number): boolean {
   return (value % 1) === 0;
 }
 
-export function isNil (value: any): boolean {
+export function isNil (value: any): value is (null|undefined) {
   return value === null || typeof (value) === 'undefined';
 }
 
-export function isString (value: any): boolean {
+export function isString (value: any): value is string {
 
   return typeof value === 'string';
 }