How can I resolve the issue of Typescript displaying an error when trying to set a property on an undefined object

Question

How can I resolve the issue of Typescript displaying an error when trying to set a property on an undefined object

My situation involves an interface:

interface IGroup{
    groupNumber:number;
    groupMembers:Array<ISeatPlanGroup>;
    totalStudentNumber:number;
  }

Every time I attempt to assign a value to the groupNumber property, the compiler throws an error saying that the property cannot be set on undefined.

              var group: IGroup;
              group.groupNumber = groupArr[i].groupNo;
              group.groupMembers=[];
              group.groupMembers.push(groupArr[i]);
              group.totalStudentNumber = 0;
              group.totalStudentNumber+=groupArr[i].studentNumber;

I also attempted to initialize it with:

group.groupNumber = 0;

But the error persists. How can this issue be resolved?

javascript angularjs typescript

Answer 1

Answer №1

When specifying your type, make sure to initialize your object properly.

let myGroup: any = {}

Answer 2

When specifying your type, make sure to initialize your object properly.

let myGroup: any = {}

Answer 3

Answer №2

let team: ITeam; does not actually create an object, it simply indicates the type of reference that team can contain. Initially, team is set to undefined.

You need to assign an object to team that conforms to the ITeam interface. For example, if you have a class called Team that implements ITeam, you would do the following:

let team: ITeam = new Team();

Keep in mind that your actual class name might be different than Team, and the constructor of the class could require arguments. The key point is that you need to assign an object to team.

Answer 4

let team: ITeam; does not actually create an object, it simply indicates the type of reference that team can contain. Initially, team is set to undefined.

You need to assign an object to team that conforms to the ITeam interface. For example, if you have a class called Team that implements ITeam, you would do the following:

let team: ITeam = new Team();

Keep in mind that your actual class name might be different than Team, and the constructor of the class could require arguments. The key point is that you need to assign an object to team.

How can I resolve the issue of Typescript displaying an error when trying to set a property on an undefined object

Answer №1

Answer №2

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