Flash cards
Review the key moves
What is the main idea behind TypeScript Definitely Typed?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ install --save-dev @types/jqueryPut the learning moves in the order that makes the concept easiest to apply.
NPM packages in the broad JavaScript ecosystem don't always have types available.
Sometimes the projects are no longer maintained, and other times they aren't interested in, agree with, or have time to use TypeScript.
Using non-typed NPM packages in TypeScript
Using untyped NPM packages with TypeScript is not type-safe because types are missing.
To help TypeScript developers use such packages, there is a community-maintained project called Definitely Typed .
Definitely Typed is a project that provides a central repository of TypeScript definitions for NPM packages which do not have types.
Example
npm install --save-dev @types/jqueryUsually, no other steps are needed after installing the declaration package.
TypeScript will automatically pick up the types when you use the package.
Editors such as Visual Studio Code will often suggest installing packages like these when types are missing.