Stringify a Javascript class that also includes objects within an array

Using JSON I am constructing a Javascript class that keep data of a players goals over a season.

Within the Constructor of the class the season is an array but the goals are contained in and additional object within the array.

class BuildGoalsDetail {
    constructor(a){
        this.season         = [];
        this.season         = new Object([]); // The problem is that this isn't getting included in when using stringify
        this.season.goals       = [];   
    }
    buildPlayerData(a0, a1){
        this.season.push(a0);
        this.season.goals.push(a1);
    }
}
    
player = new Array();
    
player.push();
player[0] = new BuildGoalsDetail();
player[0].buildPlayerData(1971,7);
player[0].season.goals.push(12);
player[0].season.goals.push(8);
player[0].season.goals.push(9);
document.write("Season: "+player[0].season+"    Goals: "+player[0].season.goals+"<br/><br/>");
    
player.push();
player[1] = new BuildGoalsDetail();
player[1].buildPlayerData(1974,7);
player[1].season.goals.push(10);
player[1].season.goals.push(12);
document.write("Season: "+player[1].season+"    Goals: "+player[1].season.goals+"<br/><br/>");
    
a0 = JSON.stringify(player);
document.write("Output of JSON:<br/>"+a0);

The output works fine but I then want to save this as JSON, when I use Stringify it only serialises the year array and not the object with the goals array.

If Stringify isn’t the best method is there another way I should be looking at?