142 lines
4.5 KiB
JavaScript
142 lines
4.5 KiB
JavaScript
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'use strict';
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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var _map2 = require('./internal/map');
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var _map3 = _interopRequireDefault(_map2);
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var _eachOf = require('./eachOf');
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var _eachOf2 = _interopRequireDefault(_eachOf);
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var _awaitify = require('./internal/awaitify');
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var _awaitify2 = _interopRequireDefault(_awaitify);
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function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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/**
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* Produces a new collection of values by mapping each value in `coll` through
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* the `iteratee` function. The `iteratee` is called with an item from `coll`
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* and a callback for when it has finished processing. Each of these callbacks
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* takes 2 arguments: an `error`, and the transformed item from `coll`. If
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* `iteratee` passes an error to its callback, the main `callback` (for the
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* `map` function) is immediately called with the error.
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*
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* Note, that since this function applies the `iteratee` to each item in
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* parallel, there is no guarantee that the `iteratee` functions will complete
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* in order. However, the results array will be in the same order as the
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* original `coll`.
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*
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* If `map` is passed an Object, the results will be an Array. The results
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* will roughly be in the order of the original Objects' keys (but this can
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* vary across JavaScript engines).
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*
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* @name map
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* @static
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* @memberOf module:Collections
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* @method
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* @category Collection
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* @param {Array|Iterable|AsyncIterable|Object} coll - A collection to iterate over.
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* @param {AsyncFunction} iteratee - An async function to apply to each item in
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* `coll`.
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* The iteratee should complete with the transformed item.
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* Invoked with (item, callback).
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* @param {Function} [callback] - A callback which is called when all `iteratee`
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* functions have finished, or an error occurs. Results is an Array of the
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* transformed items from the `coll`. Invoked with (err, results).
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* @returns {Promise} a promise, if no callback is passed
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* @example
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*
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* // file1.txt is a file that is 1000 bytes in size
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* // file2.txt is a file that is 2000 bytes in size
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* // file3.txt is a file that is 3000 bytes in size
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* // file4.txt does not exist
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*
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* const fileList = ['file1.txt','file2.txt','file3.txt'];
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* const withMissingFileList = ['file1.txt','file2.txt','file4.txt'];
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*
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* // asynchronous function that returns the file size in bytes
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* function getFileSizeInBytes(file, callback) {
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* fs.stat(file, function(err, stat) {
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* if (err) {
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* return callback(err);
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* }
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* callback(null, stat.size);
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* });
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* }
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*
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* // Using callbacks
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* async.map(fileList, getFileSizeInBytes, function(err, results) {
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* if (err) {
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* console.log(err);
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* } else {
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* console.log(results);
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* // results is now an array of the file size in bytes for each file, e.g.
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* // [ 1000, 2000, 3000]
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* }
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* });
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*
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* // Error Handling
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* async.map(withMissingFileList, getFileSizeInBytes, function(err, results) {
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* if (err) {
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* console.log(err);
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* // [ Error: ENOENT: no such file or directory ]
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* } else {
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* console.log(results);
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* }
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* });
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*
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* // Using Promises
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* async.map(fileList, getFileSizeInBytes)
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* .then( results => {
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* console.log(results);
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* // results is now an array of the file size in bytes for each file, e.g.
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* // [ 1000, 2000, 3000]
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* }).catch( err => {
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* console.log(err);
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* });
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*
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* // Error Handling
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* async.map(withMissingFileList, getFileSizeInBytes)
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* .then( results => {
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* console.log(results);
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* }).catch( err => {
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* console.log(err);
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* // [ Error: ENOENT: no such file or directory ]
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* });
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*
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* // Using async/await
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* async () => {
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* try {
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* let results = await async.map(fileList, getFileSizeInBytes);
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* console.log(results);
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* // results is now an array of the file size in bytes for each file, e.g.
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* // [ 1000, 2000, 3000]
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* }
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* catch (err) {
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* console.log(err);
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* }
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* }
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*
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* // Error Handling
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* async () => {
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* try {
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* let results = await async.map(withMissingFileList, getFileSizeInBytes);
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* console.log(results);
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* }
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* catch (err) {
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* console.log(err);
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* // [ Error: ENOENT: no such file or directory ]
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* }
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* }
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*
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*/
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function map(coll, iteratee, callback) {
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return (0, _map3.default)(_eachOf2.default, coll, iteratee, callback);
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}
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exports.default = (0, _awaitify2.default)(map, 3);
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module.exports = exports['default'];
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