Store an object in JSON to output in NgxData-Table

/*this.displayTotal = this.monthlyPayment;
this.displayPrincipal = this.displayTotal - this.displayInterest;
this.displayBalance = this.loanAmount - this.displayPrincipal; 
this.displayInterest = (this.interestRate/this.loanTerm) * this.displayBalance;
this.displayMonth = this.displayMonth;*/
//demo mocknumber:

var displayMonth = 1000;
var displayInterest = 10;
var displayPrincipal = 100;
var displayTotal = 1000;
var displayBalance = 10000;

var json = [{
  "month": this.displayMonth,
  "interest": this.displayInterest,
  "principal": this.displayPrincipal,
  "total": this.displayTotal,
  "balance": this.displayBalance,
}];

console.log(json);

var a = document.createElement('a');
a.setAttribute('href', 'data:text/plain;charset=utf-u,' + encodeURIComponent(JSON.stringify(this.json)));
a.setAttribute('download', this.filename);
a.click()