mirror of
https://github.com/denoland/deno.git
synced 2024-11-01 09:24:20 -04:00
103 lines
2.7 KiB
Markdown
103 lines
2.7 KiB
Markdown
|
# Import and Export Modules
|
||
|
|
||
|
Deno by default standardizes the way modules are imported in both JavaScript and
|
||
|
TypeScript. It follows the ECMAScript 6 `import/export` standard with one
|
||
|
caveat, the file type must be included at the end of import statement.
|
||
|
|
||
|
```js
|
||
|
import {
|
||
|
add,
|
||
|
multiply,
|
||
|
} from "./arithmetic.ts";
|
||
|
```
|
||
|
|
||
|
Dependencies are also imported directly, there is no package management
|
||
|
overhead. Local modules are imported in exactly the same way as remote modules.
|
||
|
As the examples show below, the same functionality can be produced in the same
|
||
|
way with local or remote modules.
|
||
|
|
||
|
## Local Import
|
||
|
|
||
|
In this example the `add` and `multiply` functions are imported from a local
|
||
|
`arithmetic.ts` module.
|
||
|
|
||
|
**Command:** `deno run local.ts`
|
||
|
|
||
|
```ts
|
||
|
import { add, multiply } from "./arithmetic.ts";
|
||
|
|
||
|
function totalCost(outbound: number, inbound: number, tax: number): number {
|
||
|
return multiply(add(outbound, inbound), tax);
|
||
|
}
|
||
|
|
||
|
console.log(totalCost(19, 31, 1.2));
|
||
|
console.log(totalCost(45, 27, 1.15));
|
||
|
|
||
|
/**
|
||
|
* Output
|
||
|
*
|
||
|
* 60
|
||
|
* 82.8
|
||
|
*/
|
||
|
```
|
||
|
|
||
|
## Export
|
||
|
|
||
|
In the example above the `add` and `multiply` functions are imported from a
|
||
|
locally stored arithmetic module. To make this possible the functions stored in
|
||
|
the arithmetic module must be exported.
|
||
|
|
||
|
To do this just add the keyword `export` to the beginning of the function
|
||
|
signature as is shown below.
|
||
|
|
||
|
```ts
|
||
|
export function add(a: number, b: number): number {
|
||
|
return a + b;
|
||
|
}
|
||
|
|
||
|
export function multiply(a: number, b: number): number {
|
||
|
return a * b;
|
||
|
}
|
||
|
```
|
||
|
|
||
|
All functions, classes, constants and variables which need to be accessible
|
||
|
inside external modules must be exported. Either by prepending them with the
|
||
|
`export` keyword or including them in an export statement at the bottom of the
|
||
|
file.
|
||
|
|
||
|
To find out more on ECMAScript Export functionality please read the
|
||
|
[MDN Documentation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/export).
|
||
|
|
||
|
## Remote Import
|
||
|
|
||
|
In the local import example above an `add` and `multiply` method are imported
|
||
|
from a locally stored arithmetic module. The same functionality can be created
|
||
|
by importing `add` and `multiply` methods from a remote module too.
|
||
|
|
||
|
In this case the Ramda module is referenced, including the version number. Also
|
||
|
note a JavaScript module is imported directly into a TypeSript module, Deno has
|
||
|
no problem handling this.
|
||
|
|
||
|
**Command:** `deno run ./remote.ts`
|
||
|
|
||
|
```ts
|
||
|
import {
|
||
|
add,
|
||
|
multiply,
|
||
|
} from "https://x.nest.land/ramda@0.27.0/source/index.js";
|
||
|
|
||
|
function totalCost(outbound: number, inbound: number, tax: number): number {
|
||
|
return multiply(add(outbound, inbound), tax);
|
||
|
}
|
||
|
|
||
|
console.log(totalCost(19, 31, 1.2));
|
||
|
console.log(totalCost(45, 27, 1.15));
|
||
|
|
||
|
/**
|
||
|
* Output
|
||
|
*
|
||
|
* 60
|
||
|
* 82.8
|
||
|
*/
|
||
|
```
|