what underscore means in javascript

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In JavaScript, the underscore (_) character serves various purposes and conventions. It is not a reserved keyword or operator, but rather a convention that developers often use to convey specific meanings in their code.

Naming Conventions

The underscore is commonly used in variable and function names to improve readability and convey the intended use of the identifier.

Private and Internal Members

In some coding practices, the underscore prefix indicates that a variable or function is intended for internal or private use within a module or class.

Unused Parameters

Underscore can be used as a placeholder for unused function parameters, indicating that the parameter is intentionally ignored.

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Unused Variables

Similarly, the underscore can be used to indicate that a variable is intentionally unused or ignored.

Library and Framework Usage

Underscore.js is a popular utility library for JavaScript, used for various array, collection, and functional programming tasks.

Example Usage

Here’s an example illustrating the use of underscore in variable and function names:

    function calculateTotal(_discount, price) {
      // Calculate total price after applying discount
      return price - _discount;

In this example, _discount implies that the variable is meant for internal use within the function.


The underscore character in JavaScript serves as a naming convention to improve code readability, indicate private/internal members, and more. While it has no built-in significance in the language itself, its usage can convey valuable information to developers.

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