### Installing Simplex Noise via npm

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This command installs the `simplex-noise` package from npm, saving it as a dependency in your project. It's the standard way to add the library to a JavaScript or TypeScript project.

```Bash
npm i -S simplex-noise
```

--------------------------------

### Generating 2D Simplex Noise

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This example initializes a 2D noise function using `createNoise2D()` and then demonstrates how to call it with `x` and `y` coordinates to get a noise value between -1 and 1. The function uses `Math.random()` for seeding by default.

```JavaScript
// initialize the noise function
const noise2D = createNoise2D();
// returns a value between -1 and 1
console.log(noise2D(x, y));
```

--------------------------------

### Installing Alea PRNG for Seeded Noise

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This command installs the `alea` package, a pseudorandom number generator, which can be used to provide a custom seed for the simplex noise functions instead of the default `Math.random()`.

```Bash
npm install -S alea
```

--------------------------------

### Migrating Seeded Noise Initialization (3.x to 4.x)

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This example details the API changes for initializing simplex noise with a seed when upgrading from version 3.x to 4.x. It highlights the need to use a PRNG like `alea` and to pass a fresh instance of the PRNG to each `createNoise` call for compatibility with 3.x behavior when using multiple noise functions.

```JavaScript
// 3.x
import SimplexNoise from 'simplex-noise';
const simplex = new SimplexNoise('seed');
const value2d = simplex.noise2D(x, y);
```

```JavaScript
// 4.x
// npm install -S alea
import { createNoise2D } from 'simplex-noise';
import alea from 'alea';
const noise2D = createNoise2D(alea('seed'));
const value2d = noise2D(x, y);
```

```JavaScript
// IMPORTANT: If you use multiple noise functions (for example 2d and 3d)
// and want compatible output with 3.x you will need to pass a fresh instance
// of alea to each create call. If you reuse the alea instance you will
// get different outputs compared to simplex-noise 3.x.
const seed = 'seed';
const noise2D = createNoise2D(alea(seed));
const noise3D = createNoise3D(alea(seed));
```

--------------------------------

### Generating 4D Simplex Noise

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This example initializes a 4D noise function with `createNoise4D()` and demonstrates its usage with `x`, `y`, `z`, and `w` coordinates to obtain a noise value between -1 and 1.

```JavaScript
const noise4D = createNoise4D();
console.log(noise4D(x, y, z, w));
```

--------------------------------

### Running Simplex Noise Benchmarks

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This command executes the performance benchmark script for `simplex-noise.js`, showing the operations per second for 2D, 3D, and 4D noise generation. This provides insight into the library's performance characteristics.

```Bash
$ node perf/index.js
noise2D: 72,916,215 ops/sec ±1%
noise3D: 47,855,199 ops/sec ±0%
noise4D: 35,564,111 ops/sec ±0%
```

--------------------------------

### Importing Noise Functions (ES Module)

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This snippet demonstrates how to import specific noise generation functions, such as `createNoise2D`, using ES Module syntax. This is suitable for modern JavaScript environments and bundlers.

```JavaScript
// import the noise functions you need
import { createNoise2D } from 'simplex-noise';
```

--------------------------------

### Initializing Simplex Noise with a Custom Seed

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This snippet shows how to initialize a simplex noise function with a custom seed using the `alea` PRNG. By passing a PRNG function to `createNoise2D`, you can ensure reproducible noise patterns based on the provided seed.

```JavaScript
import alea from 'alea';
// create a new random function based on the seed
const prng = alea('seed');
// use the seeded random function to initialize the noise function
const noise2D = createNoise2D(prng);
console.log(noise2D(x, y));
```

--------------------------------

### Emulating Simplex Noise 3.x API

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This snippet demonstrates how to create an object that mimics the `simplex.noise2D`, `simplex.noise3D`, and `simplex.noise4D` methods from the 3.x API, allowing for easier migration or compatibility with older codebases while using the 4.x functions.

```JavaScript
const simplex = {
  noise2D: createNoise2D(alea(seed)),
  noise3D: createNoise3D(alea(seed)),
  noise4D: createNoise4D(alea(seed))
};
```

--------------------------------

### Migrating Random Noise Initialization (3.x to 4.x)

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This snippet illustrates the change in API for initializing simplex noise without a specific seed when migrating from version 3.x to 4.x. Version 4.x introduces named exports for specific noise dimensions and a functional approach.

```JavaScript
// 3.x
import SimplexNoise from 'simplex-noise';
const simplex = new SimplexNoise();
const value2d = simplex.noise2D(x, y);
```

```JavaScript
// 4.x
// import the functions you need
import { createNoise2D } from 'simplex-noise';
const noise2D = createNoise2D();
const value2d = noise2D(x, y);
```

--------------------------------

### Requiring Noise Functions (CommonJS)

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This snippet shows how to import noise generation functions using CommonJS `require` syntax. This method is typically used in Node.js environments.

```JavaScript
// import the noise functions you need
const { createNoise2D } = require('simplex-noise');
```

--------------------------------

### Generating 3D Simplex Noise

Source: https://github.com/jwagner/simplex-noise.js/blob/main/README.md

This snippet initializes a 3D noise function using `createNoise3D()` and shows how to retrieve a noise value by passing `x`, `y`, and `z` coordinates. The output is a value between -1 and 1.

```JavaScript
const noise3D = createNoise3D();
console.log(noise3D(x, y, z));
```

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