Updated May 10, 2023
Difference Between Require vs Import
Modules are a key construct to knowing JavaScript. We’ll cover JavaScript modules: require and import during this Require vs. Import article. These modules permit you to put in writing reusable code. By using Node Package Manager (NPM), you’ll publish your module to the community. Also, NPM permits you to utilize modules created by alternative developers.
There is 2 module system you’ll select in JavaScript:
Importing modules using require and commercialism utilizing a module. Exports and exports. Importing modules using ES6 import and commercialism using ES6 export. Are there any performance edges to using one over the other? Is there the rest we must always recognize if we use ES6 modules over Node ones? Let’s attempt to solve this problem.
What is Require?
Require are accustomed to consuming modules. It permits you to incorporate modules into your programs. You’ll embrace intrinsically core Node.js modules, community-based modules (node modules), and native modules.
Let’s say we want to scan a file from the file system. The node contains a core module referred to as ‘fs’:
const fs = require('fs');
fs.readFile('./file.txt', 'utf-8', (err, data) => {
if(err) { throw err; }
console.log('data: ', data);
});As you’ll see, we tend to import the “fs” module into our program. It allows us to access any function attached to it, like “readFile”.
Require can look around for files within the following order:
Built-in core Node.js modules (like fs)
Modules in the node_modules folder.
If the module name contains a ./, / or ../, it’ll look for the directory within the given path. It matches the extensions: *.js, *.json, and *.node.
Require Features:
- You will have dynamic loading wherever the loaded module name is not predefined /static or wherever you do not load a module, providing it’s “truly required” (depending on bound code flow).
- Loading is synchronous. If you have multiple requires, they’re loaded and processed individually.
- You will have dynamic loading wherever the loaded module name is not predefined /static or wherever you do not load a module, providing it’s “truly required” (depending on bound code flow).
- Loading is synchronous. If you have multiple requires, they’re loaded and processed individually.
- The requirement is not primarily customarily based. It isn’t very sure to become customary currently that ES6 modules exist.
The actual loading of any module using require() happens in five steps.
- Resolution
- Loading
- Wrapping
- Evaluation
- Caching
The first step, the resolution, is an enclosed step wherever node.js calculates the file methods, etc., and within the second loading; the node pulls the code within the current process. In wrapping, it wraps up the code within the operation as shown higher than so sends it to VM for evaluating, eventually catching it.
So, the node is never aware of what symbols a commonJS module goes to export until and unless the module is truly evaluated. And this is often the largest distinction with ECMAScript modules, as a result of ESM being lexical. So, the exported symbols are better known before the code is truly evaluated.
What is Import?
There is a proposal for import () to operate too to form nested import statements. In contrast to the lexical import keyword, import () operate is processed during analysis (more like require).
The syntax is just like the following.
import("foo").then((module) => ).catch((err)=>);When the associate ESM module is parsed, an enclosed structure called a Module Record is made before the VM evaluates it. As a result, any error concerning the inconvenience of a couple of exported images can raise a blunder before the analysis.
Use Cases
- The on-demand module load is feasible.
- The conditional load of modules is doable.
- A promise like asynchronous handling.
Import Features:
- You will use named imports to load solely the items you would like by selection load. Which will save memory?
- Import is asynchronous (and in the current ES6 Module Loader, it is) and may perform a touch higher.
- You will use named imports to load solely the items you would like by selection load. Which will save memory?
- Import is asynchronous (and in the current ES6 Module Loader, it is) and may perform a touch higher.
- Imports don’t seem to be obtainable in node because of version 6.
- However, it is available in future versions. You’ll use it these days using transpilers similar to Traceur Compiler, Babel, or Rollup.
Head-to-Head Comparison Between Require vs Import (Infographics)
Below are the top 4 comparisons between Require vs Import:
Key Differences Between Require vs Import
Both are popular choices in the market; let us discuss some of the major differences:
- Require is more of a dynamic analysis, and import is more of a static analysis.
- Require Throws an error at runtime, and import throws an error while parsing.
- Require is Nonlexical, and Import is Lexical.
- Requires to stay where they have put the file, and imports get sorted to the top of the file.
- You always run the import at the very beginning of the file, and you can’t run it conditionally. However, you can use require inline and conditionally.
Require vs Import Comparison Table
As you can see, there are many comparisons. Let’s look at the top comparison below:
| Sr. No | Require | Import |
| 1 | Syntax:
var dep = require(“dep”); console.log(dep.bar); dep.foo(); |
Syntax:
import {foo, bar} from “dep”; console.log(bar); foo(); |
| 2 | As import remains in stage three and is not enforced by browsers natively, we cannot run any performance. Please take a look at it. | Once you use import in your code, your transpilers will require the commonJS modeling system. Therefore nowadays, each is the same. |
| 3 | Though there aren’t any performance profits at the instant, I’ll still counsel to use import over require because it’s about to be native in JS and will (just as a result of its native) perform higher than needed. | As a result, import is native; therefore, require doesn’t perform higher than import. |
| 4 | You will have dynamic loading wherever the loaded module name is not predefined. Loading is synchronous. If you have multiple requires, they’re loaded and processed individually. | You can use named imports to load solely the items you want by selection. Which will save memory? Import is asynchronous (and in the current ES6 Module Loader, it is) and may perform a touch higher. Also, the require module system is not primarily customarily based. It isn’t very sure to become customary currently that ES6 modules exist. |
Conclusion
We learned how to produce Node.js modules and use them in our code. Modules permit us to utilize code. They supply practicality that’s isolated from alternative modules. Code is less complicated to manage once in little, bite-sized chunks. This is often the thinking behind keeping functions to just one task or having files contain solely some or one part at a time. If you have a fancy app and ought to scroll through lots or thousands of lines of code, then debugging or simply understanding the app becomes tougher. Luckily JavaScript helps us out with this by having. However, you’ll write code in one file and share that code, therefore. Stay tuned to our blog for more articles like these.
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