Angular pipe for changing to any case (esp. not those included in @angular/common)

case.pipe.ts

import { PipeTransform, Pipe } from '@angular/core';
import * as changeCase from 'change-case';

type TransformFn = (val: string) => string;

@Pipe({ name: 'joeCase', pure: true })
export class CasePipe implements PipeTransform {
    /**
     * changes the case of a value
     * @param value the value to change the case of
     * @param transform the name of the change case function to use.
     * See https://www.npmjs.com/package/change-case for valid function names.
     */
    transform(value: any, transform: string) {
        if (value == null || value === undefined) {
            return '';
        }
        const strValue: string = value.toString();
        const transformFn: TransformFn = changeCase[transform];
        if (!transformFn) {
            throw new Error(
                `Cannot perform unknown transform '${transform}' to value '${value}'.
                For a list of supported transforms, see https://www.npmjs.com/package/change-case`
            );
        }
        return transformFn(strValue);
    }
}