time-to-botec

README.md (10352B)

---

 <!--
 
 @license Apache-2.0
 
 Copyright (c) 2018 The Stdlib Authors.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
    http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 
 -->
 
 # inmapAsync
 
 > Invoke a function for each element in a collection and update the collection in-place.
 
 <!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
 
 <section class="intro">
 
 </section>
 
 <!-- /.intro -->
 
 <!-- Package usage documentation. -->
 
 <section class="usage">
 
 ## Usage
 
 ```javascript
 var inmapAsync = require( '@stdlib/utils/async/inmap' );
 ```
 
 #### inmapAsync( collection, \[options,] fcn, done )
 
 Invokes a function for each element in a `collection` and updates the `collection` in-place.
 
 <!-- eslint-disable no-use-before-define -->
 
 ```javascript
 function fcn( value, index, next ) {
     setTimeout( onTimeout, value );
     function onTimeout() {
         console.log( value );
         next( null, value*index );
     }
 }
 
 function done( error, collection ) {
     if ( error ) {
         throw error;
     }
     console.log( collection === arr );
     console.log( collection );
 }
 
 var arr = [ 3000, 2500, 1000 ];
 
 inmapAsync( arr, fcn, done );
 /*
     1000
     2500
     3000
     true
     [ 0, 2500, 2000 ]
 */
 ```
 
 The `next` callback accepts two arguments: `error` and `result`. The second argument to the `next` callback is used to update the `collection` element for the corresponding collection `index`, thus mutating the input `collection`.
 
 ```javascript
 function fcn( value, index, next ) {
     setTimeout( onTimeout, value );
     function onTimeout() {
         next( null, 'beep: '+index );
     }
 }
 
 function done( error, collection ) {
     if ( error ) {
         throw error;
     }
     console.log( collection );
     // => [ 'beep: 0', 'beep: 1', 'beep: 2' ]
 }
 
 var arr = [ 3000, 2500, 1000 ];
 
 inmapAsync( arr, fcn, done );
 ```
 
 If the `next` callback is called with an `error` argument, the input `collection` may be **partially** mutated.
 
 ```javascript
 function fcn( value, index, next ) {
     setTimeout( onTimeout, value );
     function onTimeout() {
         if ( index === 1 ) {
             return next( new Error( 'boop' ) );
         }
         next( null, 'beep: '+index );
     }
 }
 
 function done( error, collection ) {
     if ( error ) {
         // Ignore error...
     }
     console.log( collection );
     // => [ 'beep: 0', 2000, 3000 ]
 }
 
 var arr = [ 1000, 2000, 3000 ];
 
 inmapAsync( arr, fcn, done );
 ```
 
 The function accepts the following `options`:
 
 -   `limit`: the maximum number of pending invocations at any one time. Default: `infinity`.
 -   `series`: `boolean` indicating whether to sequentially invoke `fcn` for each `collection` element. If `true`, the function sets `options.limit=1`. Default: `false`.
 -   `thisArg`: the execution context for `fcn`.
 
 By default, all elements are processed concurrently, which means that the function does **not** guarantee completion order. To process each `collection` element sequentially, set the `series` option to `true`.
 
 <!-- eslint-disable no-use-before-define -->
 
 ```javascript
 function fcn( value, index, next ) {
     setTimeout( onTimeout, value );
     function onTimeout() {
         console.log( value );
         next( null, value*index );
     }
 }
 
 function done( error, collection ) {
     if ( error ) {
         throw error;
     }
     console.log( collection === arr );
     console.log( collection );
 }
 
 var arr = [ 3000, 2500, 1000 ];
 
 var opts = {
     'series': true
 };
 
 inmapAsync( arr, opts, fcn, done );
 /* =>
     3000
     2500
     1000
     true
     [ 0, 2500, 2000 ]
 */
 ```
 
 To limit the maximum number of pending function invocations, set the `limit` option.
 
 <!-- eslint-disable no-use-before-define -->
 
 ```javascript
 function fcn( value, index, next ) {
     setTimeout( onTimeout, value );
     function onTimeout() {
         console.log( value );
         next( null, value*index );
     }
 }
 
 function done( error, collection ) {
     if ( error ) {
         throw error;
     }
     console.log( collection === arr );
     console.log( collection );
 }
 
 var arr = [ 3000, 2500, 1000 ];
 
 var opts = {
     'limit': 2
 };
 
 inmapAsync( arr, opts, fcn, done );
 /* =>
     2500
     3000
     1000
     true,
     [ 0, 2500, 2000 ]
 */
 ```
 
 To set the execution context of `fcn`, set the `thisArg` option.
 
 <!-- eslint-disable no-use-before-define -->
 
 ```javascript
 function fcn( value, index, next ) {
     this.count += 1;
     setTimeout( onTimeout, value );
     function onTimeout() {
         next( null, value*index );
     }
 }
 
 var arr = [ 3000, 2500, 1000 ];
 
 var context = {
     'count': 0
 };
 
 var opts = {
     'thisArg': context
 };
 
 inmapAsync( arr, opts, fcn, done );
 
 function done( error, collection ) {
     if ( error ) {
         throw error;
     }
     console.log( collection === arr );
     // => true
 
     console.log( collection );
     // => [ 0, 2500, 2000 ]
 
     console.log( context.count );
     // => 3
 }
 ```
 
 When invoked, `fcn` is provided a maximum of four arguments:
 
 -   `value`: collection value.
 -   `index`: collection index.
 -   `collection`: the input `collection`.
 -   `next`: a callback which should be called once `fcn` has finished processing a collection `value`.
 
 The actual number of provided arguments depends on function `length`. If `fcn` accepts two arguments, `fcn` is provided `value` and `next`. If `fcn` accepts three arguments, `fcn` is provided `value`, `index`, and `next`. For every other `fcn` signature, `fcn` is provided all four arguments.
 
 <!-- eslint-disable no-use-before-define -->
 
 ```javascript
 function fcn( value, i, collection, next ) {
     console.log( 'collection: %s. %d: %d', collection.join( ',' ), i, value );
     setTimeout( onTimeout, value );
     function onTimeout() {
         console.log( value );
         next( null, value*i );
     }
 }
 
 function done( error, collection ) {
     if ( error ) {
         throw error;
     }
     console.log( collection === arr );
     // => true
 
     console.log( collection );
     // => [ 0, 2500, 2000 ]
 }
 
 var arr = [ 3000, 2500, 1000 ];
 
 inmapAsync( arr, fcn, done );
 /* =>
     collection: 3000,2500,1000. 0: 3000
     collection: 3000,2500,1000. 1: 2500
     collection: 3000,2500,1000. 2: 1000
     1000
     2500
     3000
 */
 ```
 
 #### inmapAsync.factory( \[options,] fcn )
 
 Returns a `function` which invokes a function once for each element in a `collection`.
 
 ```javascript
 function fcn( value, index, next ) {
     setTimeout( onTimeout, value );
     function onTimeout() {
         console.log( value );
         next( null, value*index );
     }
 }
 
 function done( error, collection ) {
     if ( error ) {
         throw error;
     }
     console.log( collection );
 }
 
 var f = inmapAsync.factory( fcn );
 
 var arr1 = [ 3000, 2500, 1000 ];
 
 f( arr1, done );
 /* =>
     1000
     2500
     3000
     [ 0, 2500, 2000 ]
 */
 
 var arr2 = [ 300, 250, 100 ];
 
 f( arr2, done );
 /* =>
     100
     250
     300
     [ 0, 250, 200 ]
 */
 ```
 
 The function accepts the same `options` as `inmapAsync()`.
 
 </section>
 
 <!-- /.usage -->
 
 <!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
 
 <section class="notes">
 
 ## Notes
 
 -   A `collection` may be either an [`Array`][mdn-array], [`Typed Array`][mdn-typed-array], or an array-like [`Object`][mdn-object] (excluding `strings` and `functions`).
 -   If a provided function calls the `next` callback with a truthy `error` argument, the function suspends execution and immediately calls the `done` callback for subsequent `error` handling.
 -   The function invokes the `done` callback with the input `collection` provided as the second argument.
 -   The function modifies `collection` elements in-place.
 -   The function does **not** support dynamic `collection` resizing.
 -   The function does **not** skip `undefined` elements.
 -   **Neither** `inmapAsync` nor the function returned by the `factory` method **guarantee** asynchronous execution. To guarantee asynchrony, wrap the `done` callback in a function which either executes at the end of the current stack (e.g., `nextTick`) or during a subsequent turn of the event loop (e.g., `setImmediate`, `setTimeout`).
 
 </section>
 
 <!-- /.notes -->
 
 <!-- Package usage examples. -->
 
 <section class="examples">
 
 ## Examples
 
 <!-- eslint no-undef: "error" -->
 
 ```javascript
 var resolve = require( 'path' ).resolve;
 var readFile = require( '@stdlib/fs/read-file' );
 var inmapAsync = require( '@stdlib/utils/async/inmap' );
 
 var files = [
     resolve( __dirname, 'package.json' ),
     resolve( __dirname, 'README.md' )
 ];
 
 function done( error, results ) {
     if ( error ) {
         throw error;
     }
     console.log( results );
 }
 
 function read( file, next ) {
     var opts = {
         'encoding': 'utf8'
     };
     readFile( file, opts, onFile );
 
     function onFile( error, data ) {
         if ( error ) {
             error = new Error( 'unable to read file: '+file );
             return next( error );
         }
         next( null, data );
     }
 }
 
 inmapAsync( files, read, done );
 ```
 
 </section>
 
 <!-- /.examples -->
 
 <!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
 
 <section class="references">
 
 </section>
 
 <!-- /.references -->
 
 <!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
 
 <section class="links">
 
 [mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
 
 [mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
 
 [mdn-object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
 
 </section>
 
 <!-- /.links -->