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benchmark: spread operator benchmark
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Benchmark comparing `util._extend()`, `Object.assign()`,
and the spread operator for object assignment.

`util._extend()` still wins currently.

PR-URL: #18442
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
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jasnell authored and MylesBorins committed Feb 21, 2018
1 parent 442903f commit ffbad83
Showing 1 changed file with 46 additions and 0 deletions.
46 changes: 46 additions & 0 deletions benchmark/es/spread-assign.js
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'use strict';

const common = require('../common.js');
const util = require('util');

const bench = common.createBenchmark(main, {
method: ['spread', 'assign', '_extend'],
count: [5, 10, 20],
millions: [1]
});

function main({ millions, context, count, rest, method }) {
const n = millions * 1e6;

const src = {};
for (let n = 0; n < count; n++)
src[`p${n}`] = n;

let obj; // eslint-disable-line
let i;

switch (method) {
case '':
// Empty string falls through to next line as default, mostly for tests.
case '_extend':
bench.start();
for (i = 0; i < n; i++)
obj = util._extend({}, src);
bench.end(n);
break;
case 'assign':
bench.start();
for (i = 0; i < n; i++)
obj = Object.assign({}, src);
bench.end(n);
break;
case 'spread':
bench.start();
for (i = 0; i < n; i++)
obj = { ...src };
bench.end(n);
break;
default:
throw new Error('Unexpected method');
}
}

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