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https://github.com/stuk/promise-me
Code transformer to change Node-style callbacks into promises.
https://github.com/stuk/promise-me
Last synced: about 2 months ago
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Code transformer to change Node-style callbacks into promises.
- Host: GitHub
- URL: https://github.com/stuk/promise-me
- Owner: Stuk
- License: bsd-3-clause
- Created: 2012-12-07T17:22:53.000Z (about 12 years ago)
- Default Branch: master
- Last Pushed: 2017-03-16T13:36:27.000Z (almost 8 years ago)
- Last Synced: 2024-10-26T02:34:03.554Z (2 months ago)
- Language: JavaScript
- Size: 1.19 MB
- Stars: 46
- Watchers: 6
- Forks: 6
- Open Issues: 5
-
Metadata Files:
- Readme: README.markdown
- Changelog: CHANGES.markdown
- License: LICENSE
Awesome Lists containing this project
README
Promise Me [](https://travis-ci.org/Stuk/promise-me)
==========
Promise Me helps you move your code from using callbacks to using [promises](http://wiki.commonjs.org/wiki/Promises/A), for example through [Q](https://github.com/kriskowal/q), [RSVP.js](https://github.com/tildeio/rsvp.js) or [when.js](https://github.com/cujojs/when).
It parses your code and then manipulates the AST to transform the callbacks into calls to `then()`, including a rejection handler if you handle the original callback error. Think of it as a slightly smarter find-and-replace. It will probably break your code and require you to fix it.
Try the [live demo](http://stuk.github.com/promise-me/)!
Installation and usage
----------------------
```bash
$ npm install -g promise-me
$ promise-me script.js
```
### API
```javascript
var promiseMe = require("promise-me");
var before = "...";
var after = promiseMe.convert(before, options);
```
#### promiseMe.convert(code, options)
Convert the given code to use promises.
* `{string} code` String containing Javascript code.
* `{Object} options` Options for generation.
* `{Object} options.parse` Options for `esprima.parse`. See http://esprima.org/doc/ .
* `{Object} options.generate` Options for `escodegen.generate`. See https://github.com/Constellation/escodegen/wiki/API .
* `{Function} options.matcher` A function of form `(node) => boolean`. Must accept any type of node and return true if it should be transformed into `then`, using the replacer, and false if not. See https://developer.mozilla.org/en-US/docs/SpiderMonkey/Parser_API for node types.
* `{Function} options.replacer` A function of form `(node) => Node`. Must accept any type of node and return a new node to replace it that uses `then` instead of a callback. Will only get called if options.matcher returns true. See https://developer.mozilla.org/en-US/docs/SpiderMonkey/Parser_API for node types.
* `{Function} options.flattener` A function of form `(node) => Node`. Must accept any type of node, and return either return the original node, or a new node with the `then` calls flattened.
* `{Function} log` Function to call with log messages.
* Returns `{string}` The Javascript code with callbacks replaced with `.then()` functions.
Examples
--------
### Simple callback
Before:
```javascript
getDetails("Bob", function (err, details) {
console.log(details)
});
```
After:
```javascript
getDetails('Bob').then(function (details) {
console.log(details);
});
```
### Error handling
Before:
```javascript
getDetails("Bob", function (err, details) {
if (err) {
console.error(err);
return;
}
console.log(details)
});
```
After:
```javascript
getDetails('Bob').then(function (details) {
console.log(details);
}, function (err) {
console.error(err);
return;
});
```
### Nested callbacks
Before:
```javascript
getDetails("Bob", function (err, details) {
getLongLat(details.address, details.country, function(err, longLat) {
getNearbyBars(longLat, function(err, bars) {
console.log("Your nearest bar is: " + bars[0]);
});
});
});
```
After:
```javascript
getDetails('Bob').then(function (details) {
return getLongLat(details.address, details.country);
}).then(function (longLat) {
return getNearbyBars(longLat);
}).then(function (bars) {
console.log('Your nearest bar is: ' + bars[0]);
});
```
### Captured variables
Before:
```javascript
getDetails("Bob", function (err, details) {
getLongLat(details.address, details.country, function(err, longLat) {
getNearbyBars(longLat, function(err, bars) {
// Note the captured `details` variable
console.log("The closest bar to " + details.address + " is: " + bars[0]);
});
});
});
```
After:
```javascript
getDetails("Bob").then(function (details) {
getLongLat(details.address, details.country).then(function (longLat) {
return getNearbyBars(longLat);
}).then(function (bars) {
// Note the captured `details` variable
console.log("The closest bar to " + details.address + " is: " + bars[0]);
});
});
```