I have a primeng table with a dropdown for currency change. The data being in USD and dropdown has different option to update the data to different the currency rate . I have the logic that can update the data to different currency but here I am facing one challenge i.e. whenever I am selecting the currency option I am loosing the original data(i.e) in USD. How to retain the original data ?

Here is the code:

 ngDoCheck() {
    this.productionTablecopy = [...this.productionTable]; /// creating copy of original data
  }

 onDropdownChange(event) {
  const array = this.productionTablecopy;
    if (event.code == 'NOK') {
      this.getExchangeRate(array, this.NOK)
    }
    if (event.code == 'GBP') {
      this.getExchangeRate(array, this.GBP)
    }
    if (event.code == 'EUR') {
      this.getExchangeRate(array, this.EUR)
    }
    if (event.code == 'USD') {
      this.productionTable = array; /// get original data again
    }
  }

  getExchangeRate(array, exchangerate) {

    this.productionTable = array.map(obj => {
      const newObj = {};
      Object.entries(obj).forEach(([key, value]) => {
        newObj[key] = typeof value === 'number' ? value * exchangerate : value;
      });
      return newObj;
    });

  }