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docs: grammar nits in the root README (#1364)

Co-authored-by: Brad Zacher <brad.zacher@gmail.com>
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IxquitilisSaid and bradzacher committed Dec 22, 2019
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  1. +25 −25 README.md
@@ -34,24 +34,24 @@
## Getting Started
**[You can find our Getting Started docs here](./docs/getting-started/README.md)**
**[You can find our Linting FAQ / Troubleshooting docs here](./docs/getting-started/linting/FAQ.md)**
- **[You can find our Getting Started docs here](./docs/getting-started/README.md)**
- **[You can find our Linting FAQ / Troubleshooting docs here](./docs/getting-started/linting/FAQ.md)**
The documentation below will give you an overview of what this project is, why it exists and how it works at a high level.
**It is very important that you are familiar with these concepts before reporting issues**, so it is a good idea to read them before raising issues.
**It is crucial that you are familiar with these concepts before reporting issues**, so it is a good idea to read them before raising issues.
<br>
## What are ESLint and TypeScript, and how do they compare?
**ESLint** is an awesome linter for JavaScript code.
- Behind the scenes it uses a parser to turn your source code into a data format called an Abstract Syntax Tree (AST). This data format is then used by plugins to create assertions called lint rules around what your code should look or behave like.
- Behind the scenes, it uses a parser to turn your source code into a data format called an Abstract Syntax Tree (AST). This data format is then used by plugins to create assertions called lint rules around what your code should look or behave like.
**TypeScript** is an awesome static code analyzer for JavaScript code, and some additional syntax that it provides on top of the underlying JavaScript language.
- Behind the scenes it uses a parser to turn your source code into a data format called an Abstract Syntax Tree (AST). This data format is then used by other parts of the TypeScript Compiler to do things like give you feedback on issues, allow you to refactor easily etc.
- Behind the scenes, it uses a parser to turn your source code into a data format called an Abstract Syntax Tree (AST). This data format is then used by other parts of the TypeScript Compiler to do things like give you feedback on issues, allow you to refactor easily, etc.
They sound similar, right? They are! Both projects are ultimately striving to help you write the best JavaScript code you possibly can.
@@ -63,7 +63,7 @@ As covered by the previous section, both ESLint and TypeScript rely on turning y
However, it turns out that ESLint and TypeScript use _different_ ASTs to each other.

The reason for this difference is not so interesting or important, and is simply the result of different evolutions, priorities and timelines of the projects.
The reason for this difference is not so interesting or important and is simply the result of different evolutions, priorities, and timelines of the projects.

This project, `typescript-eslint`, exists primarily because of this major difference between the projects.

@@ -105,29 +105,29 @@ For example:
var x: number = 1;
```

This is not valid JavaScript code, because it contains a so-called type annotation. When the TypeScript Compiler parses this code to produce a TypeScript AST, that `: number` syntax will be represented in the tree, and this is simply not something that ESLint can understand without additional help.
This is not valid JavaScript code, because it contains a so-called type annotation. When the TypeScript Compiler parses this code to produce a TypeScript AST, the `: number` syntax will be represented in the tree, and this is simply not something that ESLint can understand without additional help.

However, we can leverage the fact that ESLint has been designed with these use-cases in mind!

It turns out that ESLint is not just one library. Instead it is composed of a few important moving parts. One of those moving parts is **the parser**. ESLint ships with a parser built in (called [`espree`](https://github.com/eslint/espree)), and so if you only ever write standard JavaScript, you don't need to care about this implementation detail.
It turns out that ESLint is not just one library. Instead, it is composed of a few important moving parts. One of those moving parts is **the parser**. ESLint ships with a built-in parser (called [`espree`](https://github.com/eslint/espree)), and so if you only ever write standard JavaScript, you don't need to care about this implementation detail.

The great thing is, though, if we want to support non-standard JavaScript syntax, all we need to do is provide ESLint with an alternative parser to use - that is a first-class use-case offered by ESLint.

Knowing we can do this is just the start of course, we then need to set about creating a parser which is capable of parsing TypeScript source code, and delivering an AST which is compatible with the one ESLint expects (with some additions for things such as `: number` as mentioned above).
Knowing we can do this is just the start, of course, we then need to set about creating a parser which is capable of parsing TypeScript source code, and delivering an AST which is compatible with the one ESLint expects (with some additions for things such as `: number`, as mentioned above).

The [`@typescript-eslint/parser`](./packages/parser/) package in this monorepo is in fact the custom ESLint parser implementation we provide to ESLint in this scenario.
The [`@typescript-eslint/parser`](./packages/parser/) package in this monorepo is, in fact, the custom ESLint parser implementation we provide to ESLint in this scenario.

The flow and transformations that happen look a little something like this:

- ESLint invokes the `parser` specified in your ESLint config ([`@typescript-eslint/parser`](./packages/parser/))

- [`@typescript-eslint/parser`](./packages/parser/) deals with all the ESLint specific configuration, and then invokes [`@typescript-eslint/typescript-estree`](./packages/typescript-estree/), an agnostic package that is only concerned with taking TypeScript source code and producing an appropriate AST.
- [`@typescript-eslint/parser`](./packages/parser/) deals with all the ESLint specific configuration and then invokes [`@typescript-eslint/typescript-estree`](./packages/typescript-estree/), an agnostic package that is only concerned with taking TypeScript source code and producing an appropriate AST.

- [`@typescript-eslint/typescript-estree`](./packages/typescript-estree/) works by invoking the TypeScript Compiler on the given source code in order to produce a TypeScript AST, and then converting that AST into a format that ESLint expects.
- [`@typescript-eslint/typescript-estree`](./packages/typescript-estree/) works by invoking the TypeScript Compiler on the given source code in order to produce a TypeScript AST and then converting that AST into a format that ESLint expects.

**Note**: This AST format is actually more broadly used than just for ESLint. It even has its own spec and is known as **[ESTree](https://github.com/estree/estree)**, which is why our package is called `typescript-estree`.
**Note**: This AST format is more broadly used than just for ESLint. It even has its own spec and is known as **[ESTree](https://github.com/estree/estree)**, which is why our package is called `typescript-estree`.

> Because [`@typescript-eslint/typescript-estree`](./packages/typescript-estree/) has a very specific purpose, it is reusable for tools with similar requirements to ESLint. It is therefore also used to power the amazing opinionated code formatter [Prettier](https://prettier.io)'s own TypeScript use-case.
> Because [`@typescript-eslint/typescript-estree`](./packages/typescript-estree/) has a very specific purpose, it is reusable for tools with similar requirements to ESLint. It is therefore also used to power the amazing opinionated code formatter [Prettier](https://prettier.io)'s TypeScript use-case.
That just about covers the parsing piece! But what about the rules? This is where our plugins come into play.

@@ -139,14 +139,14 @@ The short answer is, no.

The great news is, **there are many, many rules which will "just work"** without you having to change anything about them or provide any custom alternatives.

However, it is super important to be mindful all of the things we have covered in this README so far.
However, it is super important to be mindful of all of the things we have covered in this README so far.

- TypeScript and ESLint have similar purposes

- This means that there will be cases where TypeScript actually solves a problem for us that we previously relied on ESLint for. These two solutions could have similar aims, but different results, or be incompatible in other ways. The best way to deal with situations like this is often to disable the relevant ESLint rule and go with the TypeScript Compiler.

- TypeScript is a superset of JavaScript
- Even with the AST conversion in place in the parser, there can be things in the final AST which ESLint does not natively understand. If ESLint rules have been written in such a way that they make particular assumptions about ASTs, this can sometimes result in rules crashing. This can be mitigated in a number of ways - we can work with rule authors to make their code more robust, or we can provide alternative rules via our own [`@typescript-eslint/eslint-plugin`](./packages/eslint-plugin/).
- Even with the AST conversion in place in the parser, there can be things in the final AST which ESLint does not natively understand. If ESLint rules have been written in such a way that they make particular assumptions about ASTs, this can sometimes result in rules crashing. This can be mitigated in several ways - we can work with rule authors to make their code more robust, or we can provide alternative rules via our own [`@typescript-eslint/eslint-plugin`](./packages/eslint-plugin/).

<br>

@@ -158,19 +158,19 @@ One of the huge benefits of using TypeScript is the fact that type information c

When the transformation steps outlined above take place, we keep references to the original TypeScript AST and associated parser services, and so ESLint rules authors can access them in their rules.

We already do this in numerous rules within [`@typescript-eslint/eslint-plugin`](./packages/eslint-plugin/), for example `no-unnecessary-type-assertion` and `no-inferrable-types`.
We already do this in numerous rules within [`@typescript-eslint/eslint-plugin`](./packages/eslint-plugin/), for example, `no-unnecessary-type-assertion` and `no-inferrable-types`.

<br>

## What about Babel and `babel-eslint`?

Babel does now support parsing (but not type-checking) TypeScript source code. This is as an alternative to using the TypeScript Compiler. It also supports many other syntaxes, via plugins, which are not supported by the TypeScript Compiler. As mentioned above, `typescript-eslint` is powered by the TypeScript Compiler, so we support whatever it does.

The key trade-off can be summarized as: `babel-eslint` supports additional syntax which TypeScript itself does not, but `typescript-eslint` supports creating rules based on type information, which is not available to babel because there is no type-checker.
The key trade-off can be summarized as `babel-eslint` supports additional syntax which TypeScript itself does not, but `typescript-eslint` supports creating rules based on type information, which is not available to babel because there is no type-checker.

Because they are separate projects powered by different underlying tooling, they are currently not intended to be used together.

Some of the people involved in `typescript-eslint` are also involved in Babel and `babel-eslint`, and in this project we are working hard to align on the AST format for non-standard JavaScript syntax. This is an ongoing effort.
Some of the people involved in `typescript-eslint` are also involved in Babel and `babel-eslint`, and in this project, we are working hard to align on the AST format for non-standard JavaScript syntax. This is an ongoing effort.

<br>

@@ -180,7 +180,7 @@ I'm so glad you asked!

As you can see at the [top of this repo](#typescript-eslint), these packages are already downloaded millions of times per month, and power high profile projects across our industry.

Nevertheless, this is a 100% community driven project. From the second you install one of the packages from this monorepo, you are a part of that community.
Nevertheless, this is a 100% community-driven project. From the second you install one of the packages from this monorepo, you are a part of that community.

Please be respectful and mindful of how many hours of unpaid work go into building out all of the functionality we have introduced (in brief detail) above.

@@ -208,7 +208,7 @@ Please follow the links below for the packages you care about.

- [`@typescript-eslint/eslint-plugin`](./packages/eslint-plugin/) - An ESLint-specific plugin which, when used in conjunction with `@typescript-eslint/parser`, allows for TypeScript-specific linting rules to run.

- [`@typescript-eslint/eslint-plugin-tslint`](./packages/eslint-plugin-tslint) - An ESLint-specific plugin which runs an instance of TSLint within your ESLint setup to allow for users to more easily migrate from TSLint to ESLint.
- [`@typescript-eslint/eslint-plugin-tslint`](./packages/eslint-plugin-tslint) - An ESLint-specific plugin that runs an instance of TSLint within your ESLint setup to allow for users to more easily migrate from TSLint to ESLint.

<br>

@@ -218,7 +218,7 @@ All of the packages are published with the same version number to make it easier

We publish a canary release on every successful merge to master, so **you never need to wait for a new stable version to make use of any updates**.

Additionally, we promote the to the `latest` tag on NPM once per week, **on Mondays at 1pm Eastern**.
Additionally, we promote the to the `latest` tag on NPM once per week, **on Mondays at 1 pm Eastern**.

The latest version under the `latest` tag is:

@@ -228,7 +228,7 @@ The latest version under the `canary` tag **(latest commit to master)** is:

<a href="https://www.npmjs.com/package/@typescript-eslint/parser"><img src="https://img.shields.io/npm/v/@typescript-eslint/parser/canary.svg?style=flat-square" alt="NPM Version" /></a>

(Note: The only exceptions to the automated publishes described above are when we are in the final phases of creating the next major version of the libraries - e.g. going from `1.x.x` to `2.x.x`. During these periods, we manually publish `canary` releases until we are happy with the release and promote it to `latest`.)
(Note: The only exception to the automated publishes described above is when we are in the final phases of creating the next major version of the libraries - e.g. going from `1.x.x` to `2.x.x`. During these periods, we manually publish `canary` releases until we are happy with the release and promote it to `latest`.)

<br>

@@ -272,7 +272,7 @@ This project exists thanks to every one of the awesome people who contribute cod

## Financial Contributors

In addition to submitting code and documentation updates, you can help us sustain our community by becoming a financial contributor [[Click here to contribute - every little helps!](https://opencollective.com/typescript-eslint/contribute)]
In addition to submitting code and documentation updates, you can help us sustain our community by becoming a financial contributor [[Click here to contribute - every little bit helps!](https://opencollective.com/typescript-eslint/contribute)]

<br>

@@ -282,7 +282,7 @@ In addition to submitting code and documentation updates, you can help us sustai

### Organizations

Support this project with your organization. Your logo will show up here with a link to your website. [[Click here to contribute - every little helps!](https://opencollective.com/typescript-eslint/contribute)]
Support this project with your organization. Your logo will show up here with a link to your website. [[Click here to contribute - every little bit helps!](https://opencollective.com/typescript-eslint/contribute)]

<a href="https://opencollective.com/typescript-eslint/organization/0/website"><img src="https://opencollective.com/typescript-eslint/organization/0/avatar.svg"></a>
<a href="https://opencollective.com/typescript-eslint/organization/1/website"><img src="https://opencollective.com/typescript-eslint/organization/1/avatar.svg"></a>

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