		@@ -8,2 +8,4 @@ var measureSpeedSync = require('measure-speed').measureSpeedSync;

		console.log('Slicing an array');
		console.log('================');
		console.log('Array length: ', ARRAY_SIZE);
		@@ -40,1 +42,36 @@ console.log('Number of slices: ', SLICES);
		console.log('Using ArrayCursor', ms);


		var ARRAY_SIZE = 150000;
		var NITEMS = 10;

		console.log('');
		console.log('Slicing the array and calculating the average');
		console.log('=============================================');
		console.log('Array length: ', ARRAY_SIZE);
		console.log('Number of items: ', NITEMS);

		var array3 = getRandomArray(ARRAY_SIZE);
		var array4 = new ArrayCursor(getRandomArray(ARRAY_SIZE));

		var ms = measureSpeedSync(function () {
		var result, output = [];
		for (var i = 0; i < ARRAY_SIZE/NITEMS; i++) {
		result = array3.slice(i * NITEMS, i * NITEMS + NITEMS)
		.reduce((acc, item) => acc + item, 0);
		output.push(result);
		}
		}, { samples: 10, discard: 2 });

		console.log('Using real array', ms);

		var ms = measureSpeedSync(function () {
		var result, output = [];
		for (var i = 0; i < ARRAY_SIZE/NITEMS; i++) {
		result = array4.slice(i * NITEMS, i * NITEMS + NITEMS)
		.reduce((acc, item) => acc + item, 0);
		output.push(result);
		}
		}, { samples: 10, discard: 2 });

		console.log('Using ArrayCursor', ms);

index.js

		@@ -0,1 +1,2 @@

		function ArrayCursor(data, begin, end) {
		@@ -7,2 +8,17 @@ this.data = data;
		this.length = this.end > this.begin ? this.end - this.begin : 0;

		// if (Proxy) {
		// var handler = {
		// configurable: false,
		// enumerable: true,
		// get: function(target, name) {
		// var index = Number(name);
		// if (! isNaN(index) && index >= 0) {
		// return target.get(index);
		// }
		// return target[name];
		// }
		// };
		// return new Proxy(this, handler);
		// }
		};
		@@ -16,3 +32,4 @@
		begin = begin ? this.begin + begin : this.begin;
		end = end ? this.end + end : this.end;
		end = end \|\| this.end;
		end = end > 0 ? this.begin + end : this.end + end;
		return new ArrayCursor(this.data, begin, end);
		@@ -27,2 +44,28 @@ };

		ArrayCursor.prototype.map = function map(cb) {
		var output = [];
		for (var i = 0; i < this.length; i++) {
		output.push(cb(this.get(i), i, this));
		}
		return output;
		};

		ArrayCursor.prototype.filter = function map(cb) {
		var output = [];
		for (var i = 0; i < this.length; i++) {
		if (cb(this.get(i), i, this)) {
		output.push(this.get(i));
		}
		}
		return output;
		};

		ArrayCursor.prototype.reduce = function map(cb, initialValue) {
		var accumulator = initialValue === undefined ? this.get(0) : initialValue;
		for (var i = 0, len = this.length; i < len; i++) {
		accumulator = cb(accumulator, this.get(i), i, this);
		}
		return accumulator;
		};

		ArrayCursor.prototype.toArray = function toArray() {
		@@ -29,0 +72,0 @@ return this.data.slice(this.begin, this.end);

package.json

		{
		"name": "array-cursor",
		"version": "0.0.1",
		"version": "0.0.2",
		"description": "An immutable array that can sliced without actually mutating",
		@@ -5,0 +5,0 @@ "main": "index.js",

README.md

		@@ -46,1 +46,7 @@ Array cursor
		* toArray(): it returns a new array that is the slice of the array contained in this.data.
		* It also support various array methods: map, filter, reduce



		### Why not using a proxy to access data seamlessly ?
		As of node 8.7 proxies are so slow to instantiate that defeat completely the purpose of the library.

.npmignore

tests/index.test.js

array-cursor - npm Package Compare versions

New alerts