The History of TypeScript
A free lesson from Swipe Coding · TypeScript, level 1 · updated October 2026
By the Swipe team, founded by Colin · how we make lessons
TypeScript was created by Microsoft and first released in 2012, led by a programming-languages veteran named Anders Hejlsberg — the same person behind the C# language and, before that, Turbo Pascal and Delphi.
Which company created TypeScript?
The motivation was practical: as JavaScript codebases at Microsoft (and everywhere else) grew larger, plain JavaScript's lack of type checking made bugs harder to catch and large projects harder to maintain. TypeScript was designed specifically to add that missing safety net on top of JavaScript, without throwing away anything developers already knew.
TypeScript was designed by Microsoft to add ____ checking on top of the JavaScript developers already knew.
That design choice — every valid JavaScript file being close to valid TypeScript — is exactly why adoption grew so fast. Teams could add TypeScript to an existing JavaScript project gradually, file by file, instead of rewriting everything from scratch.
Today, TypeScript is open source and widely used far beyond Microsoft — major frameworks and libraries across the JavaScript ecosystem either are written in TypeScript or ship with TypeScript type definitions for it.
Anders Hejlsberg, the lead designer of TypeScript, also created the C# language.
Why TypeScript?
7 questions · pass with 60% — just like in the app.
What best describes TypeScript's relationship to JavaScript?
TypeScript can catch certain kinds of bugs before the program is ever run.
Before it can run in a browser or Node.js, TypeScript code must first be ____ into plain JavaScript.
Which of these is NOT a benefit TypeScript provides over plain JavaScript?
TypeScript was created by Microsoft.
TypeScript was first released in ____.
Who led the design of TypeScript at Microsoft, and also created the C# language?
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