jamie-pate/index.html

## 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>

## 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();
	});