justcoder1

## Testing with TypeScript
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<br/>
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Yes, TypeScript(TS) allows us to be strict with the `types` of data we call functions with and the types we allow to be returned - how that data should look. However, TS doesn't have any impact on our logic, or prevent a function returning data with an incorrect value.
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Therefore, the need for testing remains and TS can work with TDD to allow for cleaner tests that only test the behaviour of our code, with TS handling any edge cases.
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TS compiles down to JavaScript(JS), meaning there are many Node.js compatible testing frameworks available with great documentation. These include [Mocha](https://mochajs.org/Mocha) (testing framework) and [Chai](https://www.chaijs.com/) (assertion library) or [Jest](https://jestjs.io/) (framework _and_ library). Most frameworks behave in a similar way so the the choice is yours.
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justcoder1

# Type Basics

### Type declaration

There are several ways we can declare type in TS

ts
let word: string = "test";
let num: number = 101;
let words: string[] = ["this", "is", "an", "array", "of", "strings"];

justcoder1

**Creating a New Project**

1.	Create a folder on your computer and start your work in VSc
2.	Create a Repo on GITHub.
3.	Then put these into GIT:
git init
git add .
git commit -m "first commit"
git branch -M main
git remote add origin https://github.com/URL.git

justcoder1

// Match Function
db.articles.aggregate([ { $match : { author : "dave" } } ]);

justcoder1

// Original Functions
(hello = function() {
  return "Hello World!"
}()) // By putting the () at the end this invokes the function

// Arrow Function
hello = () => {
  return "Hello World!"
}