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How to import and export using the module object in NodeJS

Theodore Kelechukwu Onyejiaku

In NodeJs we often use modules. A module is a global object that is accessible in any NodeJs file. Node modules are reusable codes that you can create by yourself, you can use built-in ones provided by NodeJs (e.g., fs, path, os, etc.), or you can use external ones downloaded using NPM or Yarn (e.g., expressJs, mongoose, and luna).


Module object

The module object is a special object that you might not be aware of. You can use this object whenever you import or export files as modules in your project. Take a look at the code below:

module.exports.first = () => {
    console.log("First Export");
}

module.exports.second = () => {
    console.log("Second Export");
}

console.log(module);
console.log(module.exports);

From the code above, we can see that the module object contains the “exports” property, an object that contains the values we are exporting.

Note: don’t forget that the export property of the module object is an object. This is because it is actually exporting the object values that we will be importing in other codes.

Exporting and importing modules

Since the “module” is globally accessible, we do not need to specify module.exports. You can imagine it as the window object, which has methods and properties (like window.console.log()) that are called on their own (like console.log()).

Now, let’s import this module:

index.js
export1.js
exports.first = ()=>{
    console.log("first Export");
}

exports.second = ()=>{
    console.log("Second Export");
}

Based on the output above, we have imported the export1.js file. Now, as we have seen, what we exported from the export1.js file and imported into the import1.js file is an object that contains the first and second functions as values.

Exporting other values

In this case, we are referring to exporting an array:

index.js
export2.js
exports.animals = [
    "dog",
    "sheep",
    "cow",
    "horse"
]

The output shows that the animals array is a property of the exported animal array present in the exports property of the module object.

How about exporting the exports as a single variable?

Yeeaah! How about we import without the brackets? Using the last code we wrote, we can import the animal module this way too:

index.js
export2.js
const myAnimalExports = require("./export2");

console.log(myAnimalExports.animals);

Here, we have imported the myAnimalExports. So now, we can reference each of the imported. properties.

Do names matter when importing and exporting?

Yes, names matter. Make sure you import with the same name you used when exporting.

Conclusion

In conclusion, we have looked at the global module object and learned that it contains the export property, including all the values (i.e., functions, arrays, etc.) that we want to export as a module.

Thanks for your time!

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Theodore Kelechukwu Onyejiaku
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