TypeScript: Modern JavaScript Development

Defining the sheet

A spreadsheet will be a grid of fields. Every field can contain a string or an expression, as demonstrated in the following screenshot:

In lib/model/sheet.ts, we will define the sheet and create functions to parse, show and calculate all expressions in the field.

First, we will import types and functions that we will use in this file.

import { Expression, Variable, calculateExpression, Constant, Failure, FailureKind, validate, expressionToString } from "./expression"; 
import { parse, parseConstant, parseExpression} from "./parser"; 

We can define a field as an expression or a string, and a sheet as a grid of fields:

export type Field ...