Windows
Compatible applications
Quick Facts
Basic information about this file format
Extension
.MJS
File Type
JavaScript Module
Category
Programming
Best first step
Use compatible software
Quick Summary
A practical overview of the .mjs file format
The `.mjs` file extension is used for ECMAScript JavaScript modules. It signifies that the file should be treated as a module by JavaScript runtimes, both in browsers and in Node.js environments. This is important because modules have different semantics than traditional JavaScript scripts. Modules…
File extension
.MJS
File type
JavaScript Module
Category
Programming
Recommended action
Open with a trusted compatible app
How to open a .mjs file
Start with a trusted app that supports this format
- Check the file extension carefully and confirm that the file name really ends with .mjs.
- Use software that supports this file type. If one app does not work, try another compatible program for the same platform.
- Update the application if the file was created by a newer version of the software.
- Scan files from unknown sources before opening them, especially documents, archives, scripts, installers, and executable files.
What is a .mjs file?
File extension details and usage information
The .mjs file extension is used for ECMAScript JavaScript modules. It signifies that the file should be treated as a module by JavaScript runtimes, both in browsers and in Node.js environments. This is important because modules have different semantics than traditional JavaScript scripts. Modules have their own scope, meaning variables and functions declared within a module are not automatically available in the global scope. They must be explicitly exported to be used by other modules. Similarly, to use code from other modules, you must explicitly import it. This explicit import/export mechanism promotes code organization, reusability, and avoids naming conflicts. Using .mjs allows JavaScript engines to correctly parse and execute the code as a module, enabling features like import and export statements. It's a crucial part of modern JavaScript development, facilitating modular codebases and better dependency management. The use of .mjs also helps to differentiate module files from traditional JavaScript script files (typically using the .js extension), which might be interpreted differently by older JavaScript engines or build tools. This distinction is particularly important in environments where both module and script files coexist.
Software Compatibility
Programs that may open or work with .mjs files
macOS
Compatible applications
Linux
Compatible applications
Mobile
Mobile applications
Can .mjs files be converted?
Options for saving or exporting this file to another format
In many cases, a .mjs file can be converted by opening it in compatible software and using an option such as Save As, Export, or Convert. The available output formats depend on the file type and the application used.
- Use the original software that created the file when possible.
- Check whether the application supports exporting to common formats.
- Be careful with online converters when working with private, business, or sensitive files.
- If conversion fails, the file may be corrupted, incomplete, encrypted, or not actually a .mjs file.
Why can't I open a .mjs file?
Common reasons this file type may not open correctly
Wrong software
The file may require a specific program that supports the .mjs format.
Incorrect extension
The file extension may have been renamed manually, even though the actual file format is different.
Corrupted file
The file may be incomplete, damaged during download, or transferred incorrectly.
Outdated app
Your software may need to be updated before it can open newer versions of this file format.
Frequently Asked Questions
Common questions about .mjs files
To open a .mjs file, use software that supports this file format.
- Visual Studio Code
- Notepad++
- Sublime Text
- Atom
- WebStorm
Open the file in compatible software and look for options such as Save As, Export, or Convert. If no export option is available, the file may require a specialized converter or the original application that created it.
- Verify that the file extension is correct.
- Install or update compatible software.
- Try another application that supports this format.
- Check whether the file is corrupted, incomplete, or encrypted.
A file extension alone does not guarantee whether a file is safe or unsafe. Only open files from trusted sources, scan unknown files before opening them, and be especially careful with executable, script, archive, and document files.
File safety tips
Use caution with unknown files
Only open files from trusted sources. Before opening a .mjs file, scan it with antivirus software, verify that the file extension is expected, and avoid running unknown executable, installer, macro-enabled document, or script files.