Create reusable chain function javascript

Question

I trying to create reusable chaining function, but I'm stuck. Common way c.plus(5).plus(2).execute() work fine, but I have no idea how to make this reusable like below. Do you have any idea how to do this?

function chain() {
  this.i = 0;
  this.plus = (x) => {
    this.i = this.i + x;
    return this;
  };
  this.execute = () => console.log(this.i);
}
const c = new chain();
const c1 = c.plus(5);
c1.plus(2).execute(); // 7
c1.execute();// 7 instead of 5

Answer 1

The problem with your current function is that when you call plus(), you are modifying i in the original object c.

Instead, return a new chain object each time you call plus(arg), adding arg to the current value of i.

BTW it is customary in javascript to use TitleCase to name constructors. Usually chain would be Chain. FYI.

function Chain() {
  this.i = 0;
  this.plus = (x) => {
    let c = new Chain();
    c.i = this.i + x;
    return c;
  };
  this.execute = () => console.log(this.i);
}
const c = new Chain();
const c1 = c.plus(5);
c1.plus(2).execute(); // 7
c1.execute();// 7 instead of 5
c.plus(2).plus(10).execute(); // 12