Challenge 3: tsconfig

Solve a task requiring a multi-project monorepo setup.

Multi-project tsconfig

In this challenge you will process a multi-project tsconfig structure. Parse a tsconfig JSON text with ts.parseConfigFileTextToJson, and access the compilerOptions and references fields. You will read and analyze a monorepo configuration.

Exercise Read the target value

Given a tsconfig JSON text: target "ES2020", strict true, and include array with src/**/*.ts. Parse with ts.parseConfigFileTextToJson. Print the target value from the compiler options.

Show example solution

import ts from "typescript";

const configText = '{"compilerOptions": {"target": "ES2020", "strict": true}, "include": ["src/**/*.ts"]}';
const result = ts.parseConfigFileTextToJson("tsconfig.json", configText);
const target = (result.config?.compilerOptions as { target?: string })?.target;
console.log(target);

Exercise Count references

Given a tsconfig JSON text with three project references, path values ./shared, ./app, ./utils. Parse with ts.parseConfigFileTextToJson. Print the length of the references array.

Show example solution

import ts from "typescript";

const configText = '{"references": [{"path": "./shared"}, {"path": "./app"}, {"path": "./utils"}]}';
const result = ts.parseConfigFileTextToJson("tsconfig.json", configText);
const refs = result.config?.references as Array<{ path: string }>;
console.log(refs.length);

Test yourself

Which API is used to parse a tsconfig JSON text?
- ts.parseTsConfig
- ts.parseConfigFileTextToJson
- ts.loadConfig
- ts.readTsConfig
Show answer

ts.parseConfigFileTextToJson — ts.parseConfigFileTextToJson takes a file name and config text, and returns the parsed JSON. readTsConfig, parseTsConfig and loadConfig do not exist.

Access the references array

const refs = result.config?.____ as Array<{ path: string }>;

Show answer

const refs = result.config?.references as Array<{ path: string }>;

tsconfig parts

references

Project dependencies
compilerOptions

Compiler settings
include

File patterns
parseConfigFileTextToJson

Parses config text

Next lesson: Challenge 4: Mini plugin

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