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