Development

.travis.yml

@@ -1,5 +1,12 @@
 language: node_js
 node_js:
-  - "0.10"
+  - '0.12'
+  - '0.11'
+  - '0.10'
+  - '0.8'
+  - 'iojs'
+before_install:
+  - npm update -g npm
 after_script:
-  - npm run coveralls
+  - npm run coveralls
+

README.md

@@ -19,7 +19,7 @@ For use in the browser, use [browserify](https://github.com/substack/node-browse
 var cprod = require( 'compute-cprod' );
 ```
 
-#### cprod( arr[, accessor] )
+#### cprod( arr[, options] )
 
 Computes the cumulative product of an `array`. For primitive `arrays`,
 
@@ -30,7 +30,26 @@ var arr = cprod( data );
 // returns [ 1, 2, 6, 24 ]
 ```
 
-For object `arrays`, provide an accessor `function` for accessing `array` values
+The function accepts two `options`:
+
+*  __copy__: `boolean` indicating whether to return a new `array` containing the cumulative products. Default: `true`.
+*  __accessor__: accessor `function` for accessing numeric values in object `arrays`.
+
+To mutate the input `array` (e.g. when input values can be discarded or when optimizing memory usage), set the `copy` option to `false`.
+
+``` javascript
+var data = [ 1, 2, 3, 4 ];
+
+var arr = cprod( data, {
+	'copy': false
+});
+// returns [ 1, 2, 6, 24 ]
+
+console.log( data === arr );
+// returns true
+```
+
+For object `arrays`, provide an accessor `function` for accessing numeric `array` values.
 
 ``` javascript
 var data = [
@@ -40,11 +59,13 @@ var data = [
 	['baz', 4]
 ];
 
-function getValue( d ) {
+function getValue( d, i ) {
 	return d[ 1 ];
 }
 
-var arr = cprod( arr, getValue );
+var arr = cprod( arr, {
+	'accessor': getValue
+});
 // returns [ 1, 2, 6, 24 ]
 ```
 

lib/index.js

@@ -1,104 +1,75 @@
-/**
-*
-*	COMPUTE: cumprod
-*
-*
-*	DESCRIPTION:
-*		- Computes the cumulative product of an array.
-*
-*
-*	NOTES:
-*		[1]
-*
-*
-*	TODO:
-*		[1]
-*
-*
-*	LICENSE:
-*		MIT
-*
-*	Copyright (c) 2015. Philipp Burckhardt.
-*
-*
-*	AUTHOR:
-*		Philipp Burckhardt. pburckhardt@outlook.com. 2015.
-*
-*/
-
 'use strict';
 
 // MODULES //
 
-var isArray = require( 'validate.io-array' );
+var isArray = require( 'validate.io-array' ),
+	isObject = require( 'validate.io-object' ),
+	isBoolean = require( 'validate.io-boolean-primitive' ),
+	isFunction = require( 'validate.io-function' );
 
 
 // CUMULATIVE PRODUCT //
 
 /**
-* FUNCTION: cprod( arr[, accessor] )
+* FUNCTION: cprod( arr[, options] )
 *	Computes the cumulative product of an array.
 *
-* @param {Array} arr - numeric array
-* @param {Function} [accessor] - accessor function for accessing array values
-* @returns {Array} cumulative product
+* @param {Array} arr - input array
+* @param {Object} [options] - function options
+* @param {Function} [options.accessor] - accessor function for accessing array values
+* @param {Boolean} [options.copy=true] - boolean indicating whether to return new array
+* @returns {Number[]} cumulative product array
 */
-
-function cprod( arr, clbk ) {
+function cprod( arr, opts ) {
+	var copy = true,
+		clbk;
 	if ( !isArray( arr ) ) {
 		throw new TypeError( 'cprod()::invalid input argument. Must provide an array. Value: `' + arr + '`.' );
 	}
 	if ( arguments.length > 1 ) {
-		if ( typeof clbk !== 'function' ) {
-			throw new TypeError( 'cprod()::invalid input argument. Accessor must be a function. Value: `' + clbk + '`.' );
+		if ( !isObject( opts ) ) {
+			throw new TypeError( 'cprod()::invalid input argument. Options argument must be an object. Value: `' + opts + '`.' );
+		}
+		if ( opts.hasOwnProperty( 'accessor' ) ) {
+			clbk = opts.accessor;
+			if ( !isFunction ( clbk ) ) {
+				throw new TypeError( 'cprod()::invalid option. Accessor must be a function. Value: `' + clbk + '`.' );
+			}
+		}
+		if ( opts.hasOwnProperty( 'copy' ) ) {
+			copy = opts.copy;
+			if ( !isBoolean( copy ) ) {
+				throw new TypeError( 'cprod()::invalid option. Copy option must be a boolean primitive. Value: `' + copy + '`.' );
+			}
 		}
 	}
 	var len = arr.length,
-		v = new Array( len ),
-		val,
-		flg,
+		out,
+		v,
 		i;
 
+	if ( copy === true ) {
+		out = new Array( len );
+	} else {
+		out = arr;
+	}
 	if ( clbk ) {
-		val = clbk( arr[ 0 ] );
-		if ( val === 0 ) {
-			flg = true;
-		}
-		v[ 0 ] = val;
+		out[ 0 ] = clbk( arr[ 0 ], 0 );
 		for ( i = 1; i < len; i++ ) {
-			if ( flg ) {
-				v[ i ] = 0;
-				continue;
-			}
-			val = clbk( arr[ i ] );
-			if ( val === 0 ) {
-				flg = true;
-				v[ i ] = 0;
+			v = out[ i-1 ];
+			if ( v === 0 ) {
+				out[ i ] = 0;
 			} else {
-				v[ i ] = v[ i-1 ] * val;
+				out[ i ] = v * clbk( arr[ i ], i );
 			}
 		}
 	} else {
-		val = arr[ 0 ];
-		if ( val === 0 ) {
-			flg = true;
-		}
-		v[ 0 ] = val;
+		out[ 0 ] = arr[ 0 ];
 		for ( i = 1; i < len; i++ ) {
-			if ( flg ) {
-				v[ i ] = 0;
-				continue;
-			}
-			val = arr[ i ];
-			if ( val === 0 ) {
-				flg = true;
-				v[ i ] = 0;
-			} else {
-				v[ i ] = v[ i-1 ] * val;
-			}
+			out[ i ] = out[ i-1 ] * arr[ i ];
 		}
 	}
-	return v;
+	return out;
 } // end FUNCTION cprod()
 
 

package.json

@@ -44,7 +44,10 @@
     "url": "https://github.com/compute-io/cprod/issues"
   },
   "dependencies": {
-    "validate.io-array": "^1.0.3"
+    "validate.io-array": "^1.0.3",
+    "validate.io-boolean-primitive": "^1.0.0",
+    "validate.io-function": "^1.0.2",
+    "validate.io-object": "^1.0.3"
   },
   "devDependencies": {
     "chai": "2.x.x",