93 lines
1.9 KiB
Markdown
93 lines
1.9 KiB
Markdown
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# es6-promisify
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Converts callback-based functions to Promises, using a boilerplate callback function.
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## Install
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Install with [npm](https://npmjs.org/package/es6-promisify)
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```bash
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npm install es6-promisify
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```
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## Example
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```js
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const {promisify} = require("es6-promisify");
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// Convert the stat function
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const fs = require("fs");
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const stat = promisify(fs.stat);
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// Now usable as a promise!
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try {
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const stats = await stat("example.txt");
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console.log("Got stats", stats);
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} catch (err) {
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console.error("Yikes!", err);
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}
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```
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## Promisify methods
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```js
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const {promisify} = require("es6-promisify");
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// Create a promise-based version of send_command
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const redis = require("redis").createClient(6379, "localhost");
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const client = promisify(redis.send_command.bind(redis));
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// Send commands to redis and get a promise back
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try {
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const pong = await client.ping();
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console.log("Got", pong);
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} catch (err) {
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console.error("Unexpected error", err);
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} finally {
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redis.quit();
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}
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```
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## Handle multiple callback arguments, with named parameters
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```js
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const {promisify} = require("es6-promisify");
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function test(cb) {
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return cb(undefined, 1, 2, 3);
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}
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// Create promise-based version of test
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test[promisify.argumentNames] = ["one", "two", "three"];
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const multi = promisify(test);
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// Returns named arguments
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const result = await multi();
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console.log(result); // {one: 1, two: 2, three: 3}
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```
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## Provide your own Promise implementation
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```js
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const {promisify} = require("es6-promisify");
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// Now uses Bluebird
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promisify.Promise = require("bluebird");
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const test = promisify(cb => cb(undefined, "test"));
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const result = await test();
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console.log(result); // "test", resolved using Bluebird
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```
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### Tests
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Test with tape
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```bash
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$ npm test
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```
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Published under the [MIT License](http://opensource.org/licenses/MIT).
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