init

.editorconfig

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+root = true
+
+[*]
+indent_style = tab
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[{package.json,*.yml}]
+indent_style = space
+indent_size = 2

.gitattributes

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+* text=auto
+*.js text eol=lf

.gitignore

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+node_modules

.travis.yml

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+language: node_js
+node_js:
+  - '6'
+  - '4'

index.js

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+'use strict';
+const pReduce = require('p-reduce');
+
+module.exports = (iterable, iterator) => {
+	const ret = [];
+
+	return pReduce(iterable, (a, b, i) => {
+		return Promise.resolve(iterator(b, i)).then(val => {
+			ret.push(val);
+		});
+	}).then(() => ret);
+};

license

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+The MIT License (MIT)
+
+Copyright (c) Sindre Sorhus <sindresorhus@gmail.com> (sindresorhus.com)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

package.json

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+{
+  "name": "p-map-series",
+  "version": "0.0.0",
+  "description": "Map over promises serially",
+  "license": "MIT",
+  "repository": "sindresorhus/p-map-series",
+  "author": {
+    "name": "Sindre Sorhus",
+    "email": "sindresorhus@gmail.com",
+    "url": "sindresorhus.com"
+  },
+  "engines": {
+    "node": ">=4"
+  },
+  "scripts": {
+    "test": "xo && ava"
+  },
+  "files": [
+    "index.js"
+  ],
+  "keywords": [
+    "promise",
+    "map",
+    "collection",
+    "iterable",
+    "iterator",
+    "fulfilled",
+    "serial",
+    "serially",
+    "async",
+    "await",
+    "promises",
+    "bluebird"
+  ],
+  "dependencies": {
+    "p-reduce": "^1.0.0"
+  },
+  "devDependencies": {
+    "ava": "*",
+    "delay": "^1.3.1",
+    "time-span": "^1.0.0",
+    "xo": "*"
+  },
+  "xo": {
+    "esnext": true
+  }
+}

readme.md

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+# p-map-series [![Build Status](https://travis-ci.org/sindresorhus/p-map-series.svg?branch=master)](https://travis-ci.org/sindresorhus/p-map-series)
+
+> Map over promises serially
+
+Useful as a side-effect mapper. Use [`p-map`](https://github.com/sindresorhus/p-map) if you don't need side-effects, as it's concurrent.
+
+
+## Install
+
+```
+$ npm install --save p-map-series
+```
+
+
+## Usage
+
+```js
+const pMapSeries = require('p-map-series');
+
+const keywords = [
+	getTopKeyword() //=> Promise
+	'rainbow',
+	'pony'
+];
+
+let scores = [];
+
+const mapper = keyword => fetchScore(keyword).then(score => {
+	scores.push(score);
+	return {keyword, score};
+});
+
+pMapSeries(keywords, mapper).then(result => {
+	console.log(result);
+	/*
+	[{
+		keyword: 'unicorn',
+		score: 99
+	}, {
+		keyword: 'rainbow',
+		score: 70
+	}, {
+		keyword: 'pony',
+		score: 79}
+	]
+	*/
+});
+```
+
+
+## API
+
+### pMapSeries(input, mapper)
+
+Returns a `Promise` that is fulfilled when all promises in `input` and ones returned from `mapper` are fulfilled, or rejects if any of the promises reject. The fulfilled value is an `Array` of the `mapper` created promises fulfillment values.
+
+#### input
+
+Type: `Iterable<Promise|any>`
+
+Mapped over serially in the `mapper` function.
+
+#### mapper(element, index)
+
+Type: `Function`
+
+Expected to return a value. If it's a `Promise`, it's awaited before continuing with the next iteration.
+
+
+## Related
+
+- [p-each-series](https://github.com/sindresorhus/p-each-series) - Iterate over promises serially
+- [p-reduce](https://github.com/sindresorhus/p-reduce) - Reduce a list of values using promises into a promise for a value
+- [p-map](https://github.com/sindresorhus/p-map) - Map over promises concurrently
+- [More…](https://github.com/sindresorhus/promise-fun)
+
+
+## License
+
+MIT © [Sindre Sorhus](https://sindresorhus.com)

test.js

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+import test from 'ava';
+import delay from 'delay';
+import timeSpan from 'time-span';
+import m from './';
+
+const fixtureErr = new Error('fixture');
+
+test('main', async t => {
+	let index = 0;
+	const ms = 100;
+	const end = timeSpan();
+	const input = [Promise.resolve(1), 2, 3, Promise.resolve(4)];
+
+	const val = await m(input, async (x, i) => {
+		t.is(x, i + 1);
+		t.is(index, i);
+		index++;
+		await delay(ms);
+		return x * 10;
+	});
+
+	t.deepEqual(val, [10, 20, 30, 40]);
+	t.true(end() > (ms - 20));
+});
+
+test('rejection input rejects the promise', async t => {
+	t.throws(m([1, Promise.reject(fixtureErr)], () => {}), fixtureErr.message);
+	t.throws(m([1, Promise.resolve(2)], () => Promise.reject(fixtureErr)), fixtureErr.message);
+});
+
+test('handles empty iterable', async t => {
+	t.deepEqual(await m([]), []);
+});