Duplicate Array in Function

Question

I created a script where inside my object it would calculate the percentage of an array, in this same object it contains a function that calculates the sum of my percentage with my array. However when I call the function of the object responsible for the percentage in the output it duplicates my array.

const info_comprador = {
            Nome_Comprador: 'João',
            gasto_rest: [50,100,300,10,80],
            gorjetas: [],
            Total_Gasto: 0,
            Cal_Gorjeta: function() {    
                            let n = 0 
                            while (n < this.gasto_rest.length) {
                                if (this.gasto_rest[n] < 50) {
                                    this.gorjetas.unshift(this.gasto_rest[n] * 0.2);
                                } else if (this.gasto_rest[n] > 50 && this.gasto_rest[n] < 200) {
                                    this.gorjetas.unshift(this.gasto_rest[n] * .15);
                                } else {
                                    this.gorjetas.unshift(this.gasto_rest[n] * .1);
                                } n++
                            } return this.gorjetas
            },
            Cal_Total: function() {
                            let gorjeta = this.Cal_Gorjeta()
                            let n = 0
                            while (n < this.gasto_rest.length) {
                                this.Total_Gasto += this.gasto_rest[n] + gorjeta[n]
                                n ++
                            } return this.Total_Gasto
            }
} 
let gorjeta = info_comprador.Cal_Gorjeta()
let total = info_comprador.Cal_Total()
console.log(gorjeta,total)

The result that if expected would be this:

Answer 1

Is duplicating the result because you are invoking twice the method Cal_Gorjeta():

The first call is made inline:

let gorjeta = info_comprador.Cal_Gorjeta()

The second is done within the method Cal_Total():

Cal_Total: function() {
                            //Essa chamada que está duplicando o array
                            let gorjeta = this.Cal_Gorjeta()

                            let n = 0
                            while (n < this.gasto_rest.length) {
                                //Aqui você está usando variével local gorjeta
                                //quando já possui a propriedade gorjetas
                                this.Total_Gasto += this.gasto_rest[n] + gorjeta[n]

                                n ++
                            } return this.Total_Gasto
            }

To fix you can just comment on the line let gorjeta = this.Cal_Gorjeta() within the method Cal_Total or create a call condition on that line. Use the property gorjetas to calculate Total_Gasto.

const info_comprador = {
  Nome_Comprador: 'João',
  gasto_rest: [50, 100, 300, 10, 80],
  gorjetas: [],
  Total_Gasto: 0,
  Cal_Gorjeta: function() {
    let n = 0
    while (n < this.gasto_rest.length) {
      if (this.gasto_rest[n] < 50) {
        this.gorjetas.unshift(this.gasto_rest[n] * 0.2);
      } else if (this.gasto_rest[n] > 50 && this.gasto_rest[n] < 200) {
        this.gorjetas.unshift(this.gasto_rest[n] * .15);
      } else {
        this.gorjetas.unshift(this.gasto_rest[n] * .1);
      }
      n++
    }
    return this.gorjetas
  },
  Cal_Total: function() {
    //No caso eu deixei a linha comentada pois desconheço o resto do seu código
    //mas caso precise de uma condição de uso deixo como referência.
    //if (this.gorjetas == null || this.gorjetas.length === 0) this.Cal_Gorjeta()
    let n = 0
    while (n < this.gasto_rest.length) {
      this.Total_Gasto += this.gasto_rest[n] + this.gorjetas[n]
      n++
    }
    return this.Total_Gasto
  }
}
let gorjeta = info_comprador.Cal_Gorjeta()
let total = info_comprador.Cal_Total()
console.log(gorjeta, total)