Local vs. Global Installation of nodejs package - npx use case

Suppose you have installed tsc package locally in your project (npm i tsc). Note here we have not used -g flag (global installation). Then you can run tsc via "npx tsc" command. Using npx tsc instead of tsc has a few benefits related to how Node.js and npm manage dependencies and executables:

1. Local vs. Global Installation

• Global Installation: If you install TypeScript globally using npm install -g typescript, you can use the tsc command directly from anywhere. However, this means you need to manage the global TypeScript version, which can lead to version mismatches across different projects.

• Local Installation: If you install TypeScript locally in your project using npm install typescript --save-dev, the tsc command is placed in node_modules/.bin, which is not globally available in your terminal.

2. Using npx

npx is a tool that comes with npm (version 5.2.0 and higher) and is designed to execute binaries from the node_modules/.bin directory. It allows you to run commands from locally installed packages without needing to install them globally.

Benefits of Using npx tsc:

1. Consistency: Ensures you are using the project-specific version of TypeScript, avoiding potential version conflicts between projects.
2. No Global Installation Required: You don't need to install TypeScript globally, which keeps your global environment clean.
3. Ease of Use: You don't need to remember to add ./node_modules/.bin to your PATH. npx handles this automatically.

Practical Example

1. Local Installation of TypeScript:

   npm install typescript --save-dev
   

2. Using npx tsc:

   npx tsc
   

Why Not Just Use tsc?

If you run tsc without npx in a project with only a local installation of TypeScript, you'll get an error like command not found: tsc. This is because the tsc command is not available globally unless you have installed TypeScript globally.