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Tips for typing import statements in JavaScript

https://2ality.com/2017/08/typing-import-statements.html

This blog post gives tips for typing import statements more quickly, including a helpful text snippet for Visual Studio Code.

Does JavaScript’s import statement have the wrong syntax?  #

People occasionally complain that JavaScript’s import statement has it backwards. The syntax is:

import { one, two, three } from "./my-module.js"

They argue that it should be:

from './my-module.js' import {one, two, three};

As an aside, that’s how Python does imports.

Why? It would make auto-expansion easier: We’d first type the module specifier './my-module.js' and then the imported values {one, two, three}. During the latter step, the IDE has the necessary context for helping us out.

The reasons for the different order in JavaScript are:

  • It’s the same order as variable declarations.
  • It’s the same order as using require() in Node.js modules.

Given that we only write code once but read it many times, the focus should be on which version is easier to read. And there, I slightly prefer JavaScript’s current syntax.

Auto-importing  #

These days, I mostly write TypeScript and I mostly use Visual Studio Code (VSC).

There, auto-importing has gotten really good: If there is a value I want to import, I type its name, auto-expand it (Control-Space on macOS) and VSC imports it for me. I neither have to know the name of the module nor get its relative path right.

Additionally, I use the “Organize Imports” command (which has a keyboard shortcut that you can look up via the Command Palette) to:

  • Remove unused imports.
  • Show modules and imported values in a consistent order.

Manually typing import statements  #

When typing import statements manually:

  1. I import nothing via {} and auto-expand the module specifier:

    import {} from "█"

  2. I go back and auto-expand the imported values:

    import {█} from './my-module.js';

A code snippet for faster entry  #

To create a snippet for Visual Studio Code that helps with import statements, follow these steps:

  1. Execute the menu command File > Preferences > User Snippets (Mac: Code > Preferences > User Snippets).

  2. Pick the language “JavaScript”.

  3. Add this property to the JSON file:

    "import": {
    "prefix": "imp",
    "body": [
        "import ${2:values} from '${1:specifier}';$0"
    ],
    "description": "import statement"
}

Explanation:

  • Initially, place the cursor after from (position $1). The placeholder we’ll see at that position is specifier.
  • The next time we press the <tab> key, the cursor will jump to after import (position $2).
  • The last tab stop is after the semicolon (position $0).

Now editing works as follows:

  1. imp <tab>
  2. import values from '█';
  3. Use auto-expansion.
  4. import values from './my-module.js█';
  5. <tab>
  6. import █ from './my-module.js';
  7. import {█} from './my-module.js';
  8. Use auto-expansion.
  9. import {one, two, three█} from './my-module.js';
  10. <tab>
  11. import {one, two, three} from './my-module.js';█

Update 2017-09-20: A similar snippet is now built into Visual Studio Code for .js(x) files (previously, only TypeScript was supported (more information).

Further reading  #