Check out example codes for "typescript string in object property". It will help you in understanding the concepts better.

Code Example 1

protected get ButtonClass(): object {
    const buttonClass = {
      'cursor-pointer hover:shadow focus:shadow': this.Enabled,
      'opacity-40 cursor-not-allowed': !this.Enabled,
      'whitespace-no-wrap': !this.LineBreaks
    }
    // The below allows you to define object properties based on a variable.
    // If you were to assign them in the snippet above, it would cause an error.
    buttonClass[`hover:${this.Color.FocusColorClass}`] = this.Enabled;
    buttonClass[`focus:${this.Color.FocusColorClass}`] = this.Enabled;
    buttonClass[`active:${this.Color.ActiveColorClass}`] = this.Enabled;
    return buttonClass;
  }

Learn ReactJs, React Native from akashmittal.com