Object transformer

object-transformer.ts

import { Injectable } from '@angular/core';

type Checker = (any: any) => boolean;
type Transformer = (any: any) => any;

@Injectable()
export class ObjectTransformerService {
    /**
     * process data and transform it.
     * @description Checker and transformer are passed the value currently being evaluated, if the
     * checker returns a value of true the transformer will be called otherwise the code will continue processing. The
     * value the transformer returns will become the property otherwise the original property value will remain.
     * @param data can be a complex object with values, arrays and objects, array, or a primitive value.
     * @param checker receives the property/value being looped over for you to perform your logic check. Return should be a boolean.
     * @param transformer receives the property/value being looped over for transformation. Return will become the property/value
     * @returns the transformed data or original data passed it if no transformation
     */
    public process(data: any, checker: Checker, transformer: Transformer) {

        if (checker(data)) {
            return transformer(data);
        }

        if (Array.isArray(data)) {
            const array: any[] = [];
            (<any[]>data).forEach((item, index) => {
                array.push(this.process(item, checker, transformer));
            });
            return array;
        }

        if (typeof data === 'object') {
            const newObj = {};
            Object.entries(data).forEach(([key, value]) => {
                newObj[key] = value;

                if (checker(value)) {
                    newObj[key] = transformer(value);
                }
                if (value !== null && typeof value === 'object') {
                    newObj[key] = this.process(value, checker, transformer);
                }
            });
            return newObj;
        }

        return data;
    }

}