promisify-node
Wrap Node-callback functions to return Promises.
$ npm install promisify-node
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official npm registry.
Promisify Node
Stable: 0.5.0
Maintained by Tim Branyen @tbranyen.
Wraps Node modules, functions, and methods written in the Node-callback style to return Promises.
Install
npm install promisify-node
Examples
Wrap entire Node modules recursively:
var promisify = require("promisify-node");
var fs = promisify("fs");
// This function has been identified as an asynchronous function so it has
// been automatically wrapped.
fs.readFile("/etc/passwd").then(function(contents) {
console.log(contents);
});
Wrap a single function:
var promisify = require("promisify-node");
function async(callback) {
callback(null, true);
}
// Convert the function to return a Promise.
var wrap = promisify(async);
// Invoke the newly wrapped function.
wrap().then(function(value) {
console.log(value === true);
});
Wrap a method on an Object:
var promisify = require("promisify-node");
var myObj = {
myMethod: function(a, b, cb) {
cb(a, b);
}
};
// No need to return anything as the methods will be replaced on the object.
promisify(myObj);
// Intentionally cause a failure by passing an object and inspect the message.
myObj.myMethod({ msg: "Failure!" }, null).then(null, function(err) {
console.log(err.msg);
});
Wrap without mutating the original:
var promisify = require("promisify-node");
var myObj = {
myMethod: function(a, b, cb) {
cb(a, b);
}
};
// Store the original method to check later
var originalMethod = myObj.myMethod;
// Now store the result, since the 'true' value means it won't mutate 'myObj'.
var promisifiedObj = promisify(myObj, undefined, true);
// Intentionally cause a failure by passing an object and inspect the message.
promisifiedObj.myMethod({ msg: "Failure!" }, null).then(null, function(err) {
console.log(err.msg);
});
// The original method is still intact
assert(myObj.myMethod === originalMethod);
assert(promisifiedObj.myMethod !== myObj.myMethod);
Tests
Run the tests after installing dependencies with:
npm test
Current Tags
- 0.5.0 ... latest (7 years ago)
tbranyen