Question: I starting getting this error on my Angular app:

> 
> The Angular Compiler requires TypeScript >=2.7.2 and <2.8.0 but 2.8.3
>  was found instead
> 
> 
> 

and when I try to downgrade typescript to the right version doing:

`npm install -g typescript@2.7.2` it says updated 1 package.

when I verify typescript version using 
`npm view typescript version`
I still get 2.8.3

I even tried removing typescript entirely using `npm uninstall -g typescript`

but when I verify typescript version again
`npm view typescript version` I still get 2.8.3

What are the commands to properly purge and restore typescript to a previous version such as 2.7.2?

I'm running node v10.0.0 and npm v6.0.1

When I run `npm list -g typescript` I see the correct version coming 2.7.2 but still version 2.8.3 is installed somehow globally

Answer: 
You should do `npm install typescript@'>=2.7.2 <2.8.0'`. This will install the correct typescript your project needs. Make sure you run this inside your Angular project. 

On Windows, you should use double quotes instead of single quotes, like so:

```
npm install typescript@">=2.7.2 <2.8.0"

```

Otherwise, you'll get `The system cannot find the file specified.`.
I did the following:

* Delete manually the folder node\_modules
* Delete manually the file package-lock.json
* In the file package.json be sure to set the dependence of TypeScript as

```
 "typescript": "2.7.2"

```
* run npm cache clean -f
* run npm install

That work for me.