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Why Is Export Default Const Invalid?

javascript
export-default
named-exports
javascript-modules
Alex KataevbyAlex Kataev·Mar 13, 2025
TLDR

The export default const combo breaches JavaScript syntax because export default can't sync with variable declarations like const. To correctly set a constant for export, declare it first, then add the export, or pair export default with an actual value or an anonymous function/class.

Declare before Exporting:

const Tab = "Your Value"; export default Tab; // Ta-da! Your value is exported as a default

Direct Export of a Value:

export default "Your Value"; // In one line! Efficiency at its best

Deconstructing export default

In JavaScript modules, export default serves a unique role to define the "main" or "fallback" export. Consider "default" as a label, denoting what gets imported when no destructuring braces are used during the import.

Untangling export default misconceptions

  • Immutability: export default doesn't determine the exported value as constant or immutable. Unlike const.
  • Naming: The default export lacks its local name after its exported, permitting importing it under any name you desire.
  • Restrictions: Only one instance of export default can reside in a module, unlike named exports–which have no bounds.

Proficiently deploying export default

  • Declaration First: Always set your variables, functions, or classes up for declaration prior to assigning them as the default exports.
  • Unnamed Functions: Even though export default function() {} holds as valid syntax for unnamed function exportation, naming your functions will provide you with better debugging and stack trace advantages.
  • Various Exports: Use a blend of default exports paired with named exports to offer a main default value, supplemented with other features.

To-do's for Named and Default Exports

The amalgamation of default and const exports can lead to confusion, reflective of syntactical error rather than logically assembled output. Here's a brief guide for maintaining clarity in your exports:

  • Predictability: Adding explicitness by using named exports enhances code readability and eases maintenance.
  • Eases Refactoring: Maintaining distinct intentions for your exports (default/named) lightens the refactoring load.
  • Debugging Advantages: Named exports with empathetic declarative names enhance debugging, as the name remains consistent throughout the codebase.

The Craft of Exports

Harnessing the power of ES modules means grasping the impact of your export choices on your code's readability, debuggability and overall neatness.

Make Evaluation Digestible with Named Exports

Named exports give more clarity to what your module is exporting and help IDEs handle auto-imports like a breeze.

export const Tab = "Tab Value"; // I'm tabbing out... export function tabHandler() { /*...*/ } // Handle me with care

Keep Default Exports Straightforward

Keep it simple! Let the default export be your module's poster child.

export default function main() { /*...*/ } // Function of the year! 😎