time-to-botec

README.md (6418B)

---

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 @license Apache-2.0
 
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 # mapFunAsync
 
 > Invoke a function `n` times and return an array of accumulated function return values.
 
 <!-- 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 mapFunAsync = require( '@stdlib/utils/async/map-function' );
 ```
 
 #### mapFunAsync( fcn, n, \[options,] done )
 
 Invokes a function `n` times and returns an `array` of accumulated function return values.
 
 ```javascript
 function fcn( i, next ) {
     var t = 300 - (i*50);
     setTimeout( onTimeout, t );
     function onTimeout() {
         console.log( i );
         next( null, i );
     }
 }
 
 function done( error, arr ) {
     if ( error ) {
         throw error;
     }
     console.log( arr );
 }
 
 mapFunAsync( fcn, 5, done );
 /* =>
     4
     3
     2
     1
     0
     [ 0, 1, 2, 3, 4 ]
 */
 ```
 
 For each iteration, the provided function is invoked with two arguments:
 
 -   `index`: invocation index (starting from zero)
 -   `next`: callback to be invoked upon function completion
 
 The `next` callback accepts two arguments:
 
 -   `error`: error argument
 -   `result`: function result
 
 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`. If `true`, the function sets `options.limit=1`. Default: `false`.
 -   `thisArg`: the execution context for `fcn`.
 
 By default, all invocations are performed concurrently, which means that the function does **not** guarantee completion order. To invoke a function such that only one invocation is pending at any one time, set the `series` option to `true`.
 
 ```javascript
 function fcn( i, next ) {
     var t = 300 - (i*50);
     setTimeout( onTimeout, t );
     function onTimeout() {
         console.log( i );
         next( null, i );
     }
 }
 
 function done( error, arr ) {
     if ( error ) {
         throw error;
     }
     console.log( arr );
 }
 
 var opts = {
     'series': true
 };
 
 mapFunAsync( fcn, 5, opts, done );
 /* =>
     0
     1
     2
     3
     4
     [ 0, 1, 2, 3, 4 ]
 */
 ```
 
 To limit the maximum number of pending function invocations, set the `limit` option.
 
 ```javascript
 var delays = [ 300, 250, 225, 150, 100 ];
 
 function fcn( i, next ) {
     setTimeout( onTimeout, delays[ i ] );
     function onTimeout() {
         console.log( i );
         next( null, i );
     }
 }
 
 function done( error, arr ) {
     if ( error ) {
         throw error;
     }
     console.log( arr );
 }
 
 var opts = {
     'limit': 2
 };
 
 mapFunAsync( fcn, 5, opts, done );
 /* =>
     1
     0
     3
     2
     4
     [ 0, 1, 2, 3, 4 ]
 */
 ```
 
 To set the execution context of `fcn`, set the `thisArg` option.
 
 <!-- eslint-disable no-invalid-this -->
 
 ```javascript
 function fcn( i, next ) {
     this.count += 1;
     setTimeout( onTimeout, 0 );
     function onTimeout() {
         next( null, i );
     }
 }
 
 function done( error, arr ) {
     if ( error ) {
         throw error;
     }
     console.log( arr );
     // => [ 0, 1, 2, 3, 4 ]
 }
 
 var ctx = {
     'count': 0
 };
 var opts = {
     'thisArg': ctx
 };
 
 mapFunAsync( fcn, 5, opts, done );
 ```
 
 #### mapFunAsync.factory( \[options,] fcn )
 
 Returns a `function` which invokes a function `n` times and returns an `array` of accumulated function return values.
 
 ```javascript
 function fcn( i, next ) {
     var t = 300 - (i*50);
     setTimeout( onTimeout, t );
     function onTimeout() {
         console.log( i );
         next( null, i );
     }
 }
 
 function done( error, arr ) {
     if ( error ) {
         throw error;
     }
     console.log( arr );
 }
 
 var opts = {
     'series': true
 };
 
 var f = mapFunAsync.factory( opts, fcn );
 
 f( 5, done );
 /* =>
     0
     1
     2
     3
     4
     [ 0, 1, 2, 3, 4 ]
 */
 
 f( 2, done );
 /* =>
     0
     1
     [ 0, 1 ]
 */
 ```
 
 The function accepts the same `options` as `mapFunAsync()`.
 
 </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
 
 -   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.
 -   **Neither** `mapFunAsync` 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 randu = require( '@stdlib/random/base/randu' );
 var mapFunAsync = require( '@stdlib/utils/async/map-function' );
 
 function rand( i, next ) {
     var t = randu() * i;
     setTimeout( onTimeout, t );
     function onTimeout() {
         next( null, t );
     }
 }
 
 function done( error, out ) {
     if ( error ) {
         throw error;
     }
     console.log( out );
 }
 
 mapFunAsync( rand, 10, done );
 ```
 
 </section>
 
 <!-- /.examples -->
 
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 <section class="references">
 
 </section>
 
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 </section>
 
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