No index signature with a parameter of type 'number' was found on type xx

Issue

These are the types I am using:

export interface IHelpDeskTextData {
  supportPaneltext: ContactHelpdeskContex[];
  selected?: number | null;
  brandOptions?: string[];
  textPanel?: ITextPanel[];
}

export class ContactHelpdeskContex {
  public brand: string;
  public paragraphList: IParagraph[];
}
interface IParagraph {
  rowList: string[];
}

export interface ITextPanel {
  textContent: IParagraph[];
  selected: boolean;
  brand: string;
}

I have a variables with data of type:

public supportPaneltext: ContactHelpdeskContex[];
public textPanel: ITextPanel[] = [];

I try to do create a new variable via the map function of above variable:

public getLabel() {
    if (!this.supportPaneltext) {
      return;
    }

    this.textPanel = Object.values(this.supportPaneltext).map((item,i) => {
      return {
        brand: item[i].brand,
        selected: false,
        textContent: item[i].paragraphList
      }}
      )}

However, I get this error when I try to use the index [i]:

Element implicitly has an 'any' type because expression of type 'number' can't be used to index type 'ContactHelpdeskContex'.
  No index signature with a parameter of type 'number' was found on type 'ContactHelpdeskContex'.

How come, and how to solve it?

Solution

This error appear because you try index ContactHelpdeskContex with i like follow: item[i].brand. It's caused by fact that value passed to .map() method (item here) is specific element of array not array itself, you can read how map work here.

Simple remove [i]

public getLabel() {
    if (!this.supportPaneltext) {
        return;
    }

    this.textPanel = Object.values(this.supportPaneltext).map(item => ({
        brand: item.brand,
        selected: false,
        textContent: item.paragraphList
    }))
}

Answered By - Draggu