modify-str

modify-str is a small, lightweight utility that allows you to modify strings using a single, configurable function.

It is designed to be:

• Immutable & pure (no side effects)
• Predictable (clear rules when multiple options are used)
• Type-safe (written in TypeScript, ships JavaScript + type definitions)

✨ Why modify-str?

Instead of manually chaining multiple string operations:

str.trim().toUpperCase().replace(/\s+/g, "_");

You can declaratively describe what you want:

modifyStr("Hello World", {
  trim: true,
  snakeCase: true,
  toUpperCase: true,
});

This makes string transformations:

1. Easier to read

2. Easier to maintain

3. Easier to extend

Installation

npm install @amandeepsingh13/modify-str

Basic Usage

// ESM
import { modifyStr } from "@amandeepsingh13/modify-str";

const result = modifyStr("Hello World", {
  snakeCase: true,
});

console.log(result);
// hello_world

// CommonJS
const { modifyStr } = require("@amandeepsingh13/modify-str");

console.log(
  modifyStr("Hello World", { toUpperCase: true })
);
// HELLO WORLD

⚙️ Available Options

trim

| Property | Value | |--------|------| | Type | boolean | | Description | Removes leading and trailing spaces | | Example | " hi " → "hi" |

removeExtraSpaces

| Property | Value | |--------|------| | Type | boolean | | Description | Collapses multiple spaces into a single space | | Example | "hi there" → "hi there" |

capitaliseFirstChar

| Property | Value | |--------|------| | Type | boolean | | Description | Capitalizes the first character of the string | | Example | "hello" → "Hello" |

snakeCase

| Property | Value | |--------|------| | Type | boolean | | Description | Converts a string to snake_case | | Example | "Hello World" → "hello_world" |

camelCase

| Property | Value | |--------|------| | Type | boolean | | Description | Converts a string to camelCase | | Example | "hello world" → "helloWorld" |

Applying Multiple Transformations

modifyStr("  Hello World  ", {
  trim: true,
  snakeCase: true,
  toUpperCase: true,
});
// HELLO_WORLD

Conflict Resolution (Important)

If conflicting options are provided, the last option wins.

modifyStr("Hello World", {
  toUpperCase: true,
  toLowerCase: true,
});

// hello world