extends-promise - npm Package Compare versions

Comparing version 1.1.2 to 1.2.0

index.js

@@ -40,14 +40,29 @@ "use strict";
 
-	map(fn) {
-		return this.then(res => P.all(res.map(fn)));
-	}
+	map(fn, opts) {
+		const concurrency = opts && opts.concurrency;
 
-	filter(fn) {
+		if (typeof concurrency !== "number" || !isFinite(concurrency) || concurrency < 1) {
+			return this.then(res => P.all(res.map(fn)));
+		}
+
 		return this.then(res => {
-			return P
-				.all(res.map(fn))
-				.then(filters => res.filter((_, i) => filters[i]));
+			const ds = res.map(P.defer);
+			let i = concurrency;
+
+			ds.slice(0, concurrency).forEach(d => d.resolve());
+
+			return P.all(res.map((x, j) => {
+				return ds[j].promise
+					.then(() => fn(x, j, res))
+					.tap(() => ds[i] && ds[i++].resolve());
+			}));
 		});
 	}
 
+	filter(fn, opts) {
+		return this
+			.map((x, i, a) => P.all([fn(x, i, a), x]), opts)
+			.then(res => res.filter(t => t[0]).map(t => t[1]));
+	}
+
 	reduce(fn, initialValue) {
@@ -67,2 +82,14 @@ const reducer = (y, x, i, a) => P.resolve(y).then(z => fn(z, x, i, a));
 	// Methods should also be available as static
+	static defer() {
+		let resolve = null;
+		let reject = null;
+
+		const promise = new P((res, rej) => {
+			resolve = res;
+			reject = rej;
+		});
+
+		return { resolve, reject, promise };
+	}
+
 	static delay(ms, val) {
@@ -72,8 +99,8 @@ return P.resolve(val).delay(ms);
 
-	static map(val, fn) {
-		return P.resolve(val).map(fn);
+	static map(val, fn, opts) {
+		return P.resolve(val).map(fn, opts);
 	}
 
-	static filter(val, fn) {
-		return P.resolve(val).filter(fn);
+	static filter(val, fn, opts) {
+		return P.resolve(val).filter(fn, opts);
 	}
@@ -80,0 +107,0 @@

package.json

 {
   "name": "extends-promise",
-  "version": "1.1.2",
+  "version": "1.2.0",
   "description": "Micro-library that extends native promises",
@@ -5,0 +5,0 @@ "main": "index.js",

README.md

@@ -43,2 +43,27 @@ [![NPM version][npm-image]][npm-url] [![Build Status][travis-image]][travis-url] [![Coverage Status][coveralls-image]][coveralls-url] [![Dependency Status][depstat-image]][depstat-url]
 
+#### `defer(Function fn)`
+
+Creates a `promise` along with distinct `resolve` and `reject` methods. This is handy
+if you need a promise placeholder or need to promisify something non-standard. In most
+cases you are better off with `new P((resolve, reject) => {})` or `P.promisify`. Beware of
+[the deferred anti-pattern](https://github.com/petkaantonov/bluebird/wiki/Promise-anti-patterns#the-deferred-anti-pattern).
+
+```js
+const P = require("extends-promise");
+
+const deferred = P.defer();
+
+deferred.promise.then(console.log);
+deferred.resolve("Hello, World!");
+```
+
+```js
+const P = require("extends-promise");
+
+const deferred = P.defer();
+
+deferred.promise.catch(console.error);
+deferred.reject(new Error("Goodbye, World!"));
+```
+
 #### `extend(Promise)`
@@ -120,5 +145,7 @@
 
-#### `map(Function method)`
+#### `map(Function method[, options])`
 
-Similar to `[].map` but, waits for promises returned from the mapping function to resolve. NOTE: This will run all map functions concurrently.
+Similar to `[].map` but, waits for promises returned from the mapping function to resolve. By
+default all methods will be run concurrently. You may also pass a concurrency option,
+`{ concurrency : 1 }`.
 
@@ -134,6 +161,19 @@ ```js
 
-#### `filter(Function method)`
+```js
+const P = require("extends-promise");
 
-Similar to `[].filter` but waits for promises returned from the filtering function to resolve.
+P.resolve([1, 2, 3])
+	.map(res => P.delay(Math.random() * 100, res), {
+		concurrency : 3
+	})
+	// [1, 2, 3]
+	.then(console.log);
+```
 
+#### `filter(Function method[, options])`
+
+Similar to `[].filter` but waits for promises returned from the filtering function to resolve. By
+default all methods will be run concurrently. You may also pass a concurrency option,
+`{ concurrency : 1 }`.
+
 ```js
@@ -148,2 +188,13 @@ const P = require("extends-promise");
 
+```js
+const P = require("extends-promise");
+
+P.resolve([1, 2, 3, 4])
+	.filter(res => P.delay(Math.random() * 100, res % 2), {
+		concurrency : 3
+	})
+	// [1, 3]
+	.then(console.log);
+```
+
 #### `reduce(Function method[, initialValue])`
@@ -150,0 +201,0 @@

tests/functional.test.js

@@ -31,2 +31,18 @@ "use strict";
 		});
+
+		it("should accept concurrency bound", () => {
+			const concurrency = 3;
+			let running = 0;
+
+			return P
+				.map(Array(10).fill(0), () => {
+					running += 1;
+
+					assert(running <= concurrency, "Too much concurrency!");
+
+					return P
+						.delay(5)
+						.then(() => running -= 1);
+				}, { concurrency });
+		});
 	});
@@ -54,2 +70,20 @@
 		});
+
+		it("should accept concurrency bound", () => {
+			const concurrency = 3;
+			let running = 0;
+
+			return P
+				.filter([1, 2, 3, 4], x => {
+					running += 1;
+
+					assert(running <= concurrency, "Too much concurrency!");
+
+					return P
+						.delay(5)
+						.then(() => running -= 1)
+						.return(x % 2);
+				}, { concurrency })
+				.then(res => assert.deepEqual(res, [1, 3]));
+		});
 	});
@@ -56,0 +90,0 @@

tests/helpers.test.js

@@ -11,2 +11,23 @@ "use strict";
 describe("Helpers", () => {
+	describe(".defer", () => {
+		it("should be able to resolve a deferred promise", () => {
+			const d = P.defer();
+
+			d.resolve(1);
+
+			return d.promise.then(res => assert.strictEqual(res, 1));
+		});
+
+		it("should be able to reject a deferred promise", () => {
+			const d = P.defer();
+			const err = new Error();
+
+			d.reject(err);
+
+			return d.promise
+				.then(() => P.reject(new Error()))
+				.catch(res => assert.strictEqual(res, err));
+		});
+	});
+
 	describe(".return", () => {
@@ -13,0 +34,0 @@ it("should be able to return value", () => {

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Improved metrics

Total package byte prevSize

23438

increased by15.25%

Lines of code

529

increased by13.03%

Number of lines in readme file

261

increased by24.29%

No dependency changes