How to Run Multiple Scripts in Parallel with Yarn - 面试题

In Yarn, running multiple scripts in parallel can be achieved through various methods, with common approaches including the use of concurrently, npm-run-all, or simple shell command combinations.

Using concurrently: concurrently is an npm package designed to execute multiple commands simultaneously. First, install this package:
```
bash
npm install concurrently --save-dev
```
Then, in the package.json scripts section, define the use of concurrently to run multiple scripts:
```
json
{
  "scripts": {
    "start": "concurrently "npm run script1" "npm run script2""
  }
}
```
Here, script1 and script2 represent the names of the scripts you wish to run in parallel. This command launches both scripts, executing them concurrently.
Using npm-run-all: Another tool is npm-run-all, which supports running multiple npm scripts either in parallel or sequentially. First, install this utility:
```
bash
npm install npm-run-all --save-dev
```
Use it in package.json to run scripts in parallel:
```
json
{
  "scripts": {
    "start": "npm-run-all --parallel script1 script2"
  }
}
```
Applying the --parallel flag ensures that script1 and script2 execute in parallel.
Using Shell Commands: If you prefer not to introduce additional dependencies, shell commands can be used to run scripts in parallel:
```
json
{
  "scripts": {
    "start": "npm run script1 & npm run script2"
  }
}
```
The & symbol enables commands to run concurrently on Unix-like systems. On Windows, the start command achieves the same effect.

All these methods facilitate parallel script execution with Yarn, and the choice depends on project requirements and team preferences.