Why does JavaScript use an underscore prefix for \'private\' methods and variables?

Understanding the Significance of the Underscore Prefix in JavaScript

In contrast to Python's explicit private class methods, the underscore prefix in JavaScript is merely a convention. JavaScript lacks any inherent semantics attached to identifiers beginning with underscores.

However, this convention holds practical significance in JavaScript's absence of native encapsulation:

• Documentation: Underscore-prefixed identifiers explicitly indicate non-public API elements, discouraging indiscriminate usage from outside the implementing class.
• Clarity: The prefix enhances code readability by distinguishing private from public elements.
• Intent: It denotes that the implementation should remain concealed to maintain encapsulation principles.

Consider the JavaScript code example:

function AltTabPopup() {
    this._init();
}

AltTabPopup.prototype = {
    _init : function() {
        ...
    }
}

Here, _init is a private method intended to be invoked only within the class, while _currentApp, _currentWindow, and other variables are also considered non-public.

While the underscore prefix itself doesn't enforce privacy, it serves as a widely accepted convention that signifies and communicates the author's intended level of visibility within the codebase.

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