Skip to content
New this month 24 fresh C++, C#, F#, JavaScript, TypeScript and Lua courses just landed. Browse new releases Use code WELCOME10 for 10% off your first order · 14-day refund
WisdomCharms — home
Cart 0 items in cart
Web Development Intermediate New

tsconfig Strict Mode: A One-Hour Migration Guide

Turn on strict mode in a real codebase without drowning in thousands of new errors.

Rated 5.0 out of 5 from 2 reviews 32 students

MH Created by Marcus Hale

  • Last updated August 2026
  • English
  • 1h 14m of material
  • 9 lessons

What you will learn

6 concrete outcomes

Every bullet below is something you will have built, shipped or be able to explain by the time you finish the last lesson.

  • Enable the eight strict flags in an order that keeps the error count manageable
  • Recognise and mechanically fix the common error pattern each flag produces
  • Migrate one directory at a time using project references and scoped configs
  • Add a continuous integration ratchet so strictness never regresses
  • Decide whether noUncheckedIndexedAccess and exactOptionalPropertyTypes are worth it
  • Explain the migration plan to a sceptical team with concrete numbers

Course curriculum

4 modules · 9 lessons · 1h 14m of material

2 lessons running 16m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

3 lessons running 26m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

2 lessons running 16m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

2 lessons running 16m in total. Each lesson ships with the finished source files and a short written recap, so you can follow along in your own editor and skim the module again later.

Lesson-by-lesson titles, code downloads and exercises live inside the course library you get access to straight after checkout.

4 modules · 9 lessons

1h 14m total length

Requirements

Short list, and deliberately so. If you meet these you can start today.

  • An existing TypeScript project, ideally one where strict is currently off
  • TypeScript 5.0 or newer and access to your repository configuration

About this course

Enabling strict in an existing tsconfig usually produces a wall of errors, a quick revert and a promise to do it later. This mini-course gives you the staged approach that actually finishes, and it takes about an hour.

Strict mode is not one switch, it is eight. You will enable them one at a time in the order that produces the fewest cascading errors: noImplicitAny, strictNullChecks, strictFunctionTypes, strictBindCallApply, strictPropertyInitialization, noImplicitThis, useUnknownInCatchVariables and alwaysStrict. Each lesson explains what the flag catches, shows the error patterns it produces and gives a mechanical fix for each pattern.

The last two lessons cover the surrounding strategy: using include and exclude plus per-directory configs to migrate a subtree at a time, adding a ratchet in continuous integration so the error count can only fall, and the related flags worth adopting next, noUncheckedIndexedAccess, exactOptionalPropertyTypes and noImplicitOverride, with a realistic assessment of the effort each demands.

Topics covered

Frequently asked questions

Still unsure about something? Write to misteryjj100@gmail.com and a human answers, usually the same working day.

The staged approach was developed on codebases in the hundreds of thousands of lines. The per-directory technique is what makes size manageable rather than fatal.

No. Most strict errors are fixed by narrowing, initialising or adjusting a signature. The course shows the mechanical fix for each pattern so it stays repetitive rather than creative.

Yes. The staging module uses project references and a base config extended per package, which lets one workspace run strict while its neighbours are still being migrated.

Checkout is handled on our provider's secure payment page. The moment your payment clears we email your personal access link and access code to the address you used at checkout, and the same link appears in your account library. There is nothing to install and nothing to wait for.

Email misteryjj100@gmail.com within 14 days of your purchase, quote your order number, and we refund the full amount to your original payment method. No form to fill in and no questions about how much of the course you watched.

What students say

Reviews are written by people who bought this course. We publish the critical ones too.

5.0

Rated 5.0 out of 5

Course rating · 2 reviews

Rating distribution

  • 5 stars 100%
  • 4 stars 0%
  • 3 stars 0%
  • 2 stars 0%
  • 1 star 0%
  • EC

    Emily Carrington

    Frontend lead

    Jul 2026
    Rated 5.0 out of 5

    The ratchet is the whole point

    Turning strict on across four hundred files used to mean a branch nobody would ever review. Enabling one flag at a time, recording the error count and failing the build only when it climbs got us to full strict over six weeks with no big-bang pull request. That approach is worth far more than nine pounds.
  • TH

    Tomás Herrera

    TypeScript developer

    Jan 2026
    Rated 5.0 out of 5

    Eight flags, taken one at a time

    I had been treating strict as a single switch and losing to it repeatedly. Breaking it into the eight underlying options, then sequencing those from least painful to worst, is such an obvious framing and nobody else seems to bother.

Your instructor

MH

Marcus Hale

Web engineer and JavaScript educator

  • 259 students taught
  • 12 courses published
  • 4.7 instructor rating
  • JavaScript
  • TypeScript
  • React
  • Node.js

Marcus has shipped front ends for two ad-tech startups and one very large retailer, which taught him more about performance budgets than any blog post could. He teaches JavaScript and TypeScript from the runtime up — event loop first, framework second — then follows the same code through Node on the server side. Every one of his courses ends with a deployed application rather than a folder of exercises. He writes a weekly newsletter on browser performance.

See every course by Marcus Hale
$9 USD

One-time payment · lifetime access

The WisdomCharms dispatch

One useful email a week. No fluff, no spam.

New course releases, discount codes before anyone else, and a short, practical breakdown of one technique — a prompt pattern, a C++ idiom, a TypeScript trick — that you can use the same day.

  • Subscriber-only launch pricing
  • Unsubscribe in one click
  • We never sell your address

By subscribing you agree to our Privacy Policy. Questions? Write to misteryjj100@gmail.com.