jamie-pate · September 20, 2017 22:52
diff --git a/index.html b/index.html
 <!DOCTYPE html>
 <html>
 <head>
 	<meta charset="utf-8"/>
 	<title>Array_splice_or_hand_copy #jsbench #jsperf</title>
 	<script src="https://cdnjs.cloudflare.com/ajax/libs/benchmark/1.0.0/benchmark.min.js"></script>
 	<script src="./suite.js"></script>
 </head>
 <body>
 	<h1>Open the console to view the results</h1>
 	<h2><code>cmd + alt + j</code> or <code>ctrl + alt + j</code></h2>
 </body>
 </html>
diff --git a/suite.js b/suite.js
 "use strict";

 (function (factory) {
 	if (typeof Benchmark !== "undefined") {
 		factory(Benchmark);
 	} else {
 		factory(require("benchmark"));
 	}
 })(function (Benchmark) {
 	var suite = new Benchmark.Suite;

 	Benchmark.prototype.setup = function () {
 		Array.from = Array.from || function(a) {
 		    var result = new Array(a.length), len = a.length;
 		    for (i = 0; i < len; ++i) {
 		        result[i] = a[i] === undefined ? null : a[i];
 		    }
 		    return result;
 		}
 		
 		var
 		    N = 10000;
 		    bigArray = JSON.stringify(Array.from(new Array(N)).map(function(e, i) { return {oi: i, i:i} })),
 		    index = Math.round(N/20),
 		    after = Math.round(N/2);
 		function verify(arr) {
 		    for (i = 0; i < arr.length; ++i) {
 		       if (arr[i].i !== i) {
 		           console.error(i, arr[i]);
 		           console.error('i doesnt match ' + i + ' != ' + arr[i].i);
 		           debugger;
 		           throw new Error('i doesnt match ' + i + ' != ' + arr[i].i);
 		       }
 		       var expectedIndex = i;
 		       if (i === after) {
 		           expectedIndex = index;
 		       } else if (i >= index && i < after) {
 		           expectedIndex = i + 1;
 		       }
 		       if (arr[i].oi !== expectedIndex) {
 		           console.error(arr[i]);
 		           console.log('oi doesnt match ' + i + ' != ' + arr[i].oi);
 		           debugger;
 		           throw new Error('oi doesnt match ' + i + ' != ' + arr[i].oi);
 		       }
 		    }
 		}
 		
 		function copy(item) { return Object.assign({}, item); }
 	};

 	Benchmark.prototype.teardown = function () {
 		verify(newArray);
 	};

 	suite.add("copy by hand", function () {
 		// copy by hand
 		var newArray = JSON.parse(bigArray),
 		    i,
 		    row = newArray[index];
 		for (i = index + 1; i <= after; ++i) {
 		    --newArray[i].i;
 		    newArray[i - 1] = newArray[i];
 		}
 		row.i = after;
 		newArray[after] = row;
 	});

 	suite.add("copy by slice", function () {
 		// copy by slice
 		var newArray = JSON.parse(bigArray),
 		    middle = newArray.slice(index + 1, after + 1),
 		    row = newArray[index],
 		    end = newArray.slice(after + 1);
 		middle.forEach(function(m) { --m.i });
 		row.i = after;
 		newArray = newArray.slice(0, index).concat(middle).concat([row]).concat(end);
 	});

 	suite.add("copy by splice", function () {
 		// copy by splice
 		var newArray = JSON.parse(bigArray),
 		    row = newArray[index],
 		    middle = newArray.slice(index + 1, after + 1);
 		    
 		middle.forEach(function(m) { --m.i });
 		row.i = after;
 		
 		newArray.splice.apply(newArray, [index, after - index + 1].concat(middle).concat([row]));
 	});

 	suite.on("cycle", function (evt) {
 		console.log(" - " + evt.target);
 	});

 	suite.on("complete", function (evt) {
 		console.log(new Array(30).join("-"));

 		var results = evt.currentTarget.sort(function (a, b) {
 			return b.hz - a.hz;
 		});

 		results.forEach(function (item) {
 			console.log((idx + 1) + ". " + item);
 		});
 	});

 	console.log("Array_splice_or_hand_copy #jsbench #jsperf");
 	console.log(new Array(30).join("-"));
 	suite.run();
 });
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8"/>
	<title>Array_splice_or_hand_copy #jsbench #jsperf</title>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/benchmark/1.0.0/benchmark.min.js"></script>
	<script src="./suite.js"></script>
	</head>
	<body>
	<h1>Open the console to view the results</h1>
	<h2><code>cmd + alt + j</code> or <code>ctrl + alt + j</code></h2>
	</body>
	</html>
	"use strict";

	(function (factory) {
	if (typeof Benchmark !== "undefined") {
	factory(Benchmark);
	} else {
	factory(require("benchmark"));
	}
	})(function (Benchmark) {
	var suite = new Benchmark.Suite;

	Benchmark.prototype.setup = function () {
	Array.from = Array.from \|\| function(a) {
	var result = new Array(a.length), len = a.length;
	for (i = 0; i < len; ++i) {
	result[i] = a[i] === undefined ? null : a[i];
	}
	return result;
	}

	var
	N = 10000;
	bigArray = JSON.stringify(Array.from(new Array(N)).map(function(e, i) { return {oi: i, i:i} })),
	index = Math.round(N/20),
	after = Math.round(N/2);
	function verify(arr) {
	for (i = 0; i < arr.length; ++i) {
	if (arr[i].i !== i) {
	console.error(i, arr[i]);
	console.error('i doesnt match ' + i + ' != ' + arr[i].i);
	debugger;
	throw new Error('i doesnt match ' + i + ' != ' + arr[i].i);
	}
	var expectedIndex = i;
	if (i === after) {
	expectedIndex = index;
	} else if (i >= index && i < after) {
	expectedIndex = i + 1;
	}
	if (arr[i].oi !== expectedIndex) {
	console.error(arr[i]);
	console.log('oi doesnt match ' + i + ' != ' + arr[i].oi);
	debugger;
	throw new Error('oi doesnt match ' + i + ' != ' + arr[i].oi);
	}
	}
	}

	function copy(item) { return Object.assign({}, item); }
	};

	Benchmark.prototype.teardown = function () {
	verify(newArray);
	};

	suite.add("copy by hand", function () {
	// copy by hand
	var newArray = JSON.parse(bigArray),
	i,
	row = newArray[index];
	for (i = index + 1; i <= after; ++i) {
	--newArray[i].i;
	newArray[i - 1] = newArray[i];
	}
	row.i = after;
	newArray[after] = row;
	});

	suite.add("copy by slice", function () {
	// copy by slice
	var newArray = JSON.parse(bigArray),
	middle = newArray.slice(index + 1, after + 1),
	row = newArray[index],
	end = newArray.slice(after + 1);
	middle.forEach(function(m) { --m.i });
	row.i = after;
	newArray = newArray.slice(0, index).concat(middle).concat([row]).concat(end);
	});

	suite.add("copy by splice", function () {
	// copy by splice
	var newArray = JSON.parse(bigArray),
	row = newArray[index],
	middle = newArray.slice(index + 1, after + 1);

	middle.forEach(function(m) { --m.i });
	row.i = after;

	newArray.splice.apply(newArray, [index, after - index + 1].concat(middle).concat([row]));
	});

	suite.on("cycle", function (evt) {
	console.log(" - " + evt.target);
	});

	suite.on("complete", function (evt) {
	console.log(new Array(30).join("-"));

	var results = evt.currentTarget.sort(function (a, b) {
	return b.hz - a.hz;
	});

	results.forEach(function (item) {
	console.log((idx + 1) + ". " + item);
	});
	});

	console.log("Array_splice_or_hand_copy #jsbench #jsperf");
	console.log(new Array(30).join("-"));
	suite.run();
	});