Object vs Dictionary

[daiyam]

let foo = {} shouldn't add any instance methods (no toString())

Can't be replaced with Map due to performance but maybe with let foo = Object.create(null)
[source]

[daiyam]

Object.create(null) has a performance impact over {}

bracket-0  x 50,340,464 ops/sec ±1.57% (80 runs sampled)
create-0   x  6,586,789 ops/sec ±1.16% (82 runs sampled)
bracket-10 x  1,962,417 ops/sec ±1.81% (85 runs sampled)
create-10  x  3,593,103 ops/sec ±1.41% (83 runs sampled)
bracket-50 x    527,150 ops/sec ±1.02% (87 runs sampled)
create-50  x    409,165 ops/sec ±1.66% (82 runs sampled)

[daiyam]

var Empty = function () {};
Empty.prototype = Object.create(null);

bracket-0  x 51,518,693 ops/sec ±1.06% (83 runs sampled)
create-0   x  6,734,177 ops/sec ±0.72% (85 runs sampled)
empty-0    x 48,797,420 ops/sec ±0.90% (83 runs sampled)
bracket-10 x  1,998,575 ops/sec ±1.73% (85 runs sampled)
create-10  x  4,049,831 ops/sec ±1.75% (81 runs sampled)
empty-10   x  3,967,430 ops/sec ±1.42% (79 runs sampled)
bracket-50 x    527,756 ops/sec ±1.62% (84 runs sampled)
create-50  x    415,486 ops/sec ±1.63% (82 runs sampled)
empty-50   x    399,566 ops/sec ±1.18% (84 runs sampled)

[daiyam]

33% performance hit under IE11

[daiyam]

nodejs/node#11930

[daiyam]

• https://jsperf.com/create-object-of-size-0
• https://jsperf.com/create-object-of-size-10
• https://jsperf.com/create-object-of-size-50

	bracket-0	empty-0	reset-0	array-0	bracket-10	empty-10	reset-10	array-10	func-10	bracket-50	empty-50	reset-50	array-50
node@v4.9.1	109,907,583	105,466,334	8,743,182	78,350,599	4,406,246	13,223,237	2,683,376	7,205,675		1,144,215	1,749,112	889,232	1,101,705
node@v5.12.0	113,345,693	102,650,519	8,312,589	77,786,292	4,353,311	13,121,804	2,580,772	6,968,404		1,141,371	1,727,816	879,235	1,050,795
node@v6.17.1	112,632,002	104,217,457	8,953,358	73,174,063	4,280,500	12,123,103	2,679,092	5,929,585		1,185,816	1,576,575	920,085	942,908
node@v7.10.1	109,604,064	103,486,865	9,730,631	67,193,700	4,136,310	13,510,461	2,745,809	6,625,923		1,131,324	2,074,380	891,612	1,103,642
node@v8.16.1	577,109,255	577,541,417	10,995,557	163,782,029	584,986,515	570,363,456	7,784,466	4,007,669		578,853,931	146,943,847	3,469,325	319,266
node@v9.11.2	573,250,882	579,088,774	10,210,901	163,361,657	577,893,353	564,332,546	7,647,957	3,999,307		569,185,806	146,498,802	3,605,298	326,008
node@v10.16.3	846,748,656	847,818,922	14,143,608	234,424,951	846,419,013	829,941,581	9,663,466	4,002,362	842,223,299	841,369,330	50,016,379	4,071,938	563,336
node@v11.15.0	871,113,934	867,072,326	17,837,961	234,741,809	868,879,097	830,747,080	11,285,773	4,162,517		443,771,973	22,248,852	4,042,228	546,649
node@v12.10.0	865,620,208	865,098,901	16,935,234	230,608,203	865,283,323	819,034,873	10,259,036	4,317,446		861,477,932	51,960,711	3,509,108	572,270
Chrome 40.0.2214	117,253,898	200,702,714	8,605,628	111,927,257	2,806,459	45,365,271	2,088,161	7,778,870	43,764,022
Chrome 50.0.2661					2,975,273	56,494,980	1,971,249	6,245,400
Chrome 76.0.3809	872,055,316	872,055,316	17,073,572	235,098,124	870,953,492	827,488,786	10,080,714	5,016,334	827,901,409	855,660,709	209,650,147	3,470,330	286,306
Firefox 47.0.0	1,573,406,353	11,870,567	3,633,647	5,737,666	1,637,340,851	15,805,276	4,189,813	287,772	13,917,884
Firefox 69.0.0	1,298,433,421	1,309,207,963	9,683,672	1,033,503,590	1,293,184,332	13,946,399	6,304,625	1,131,430	14,233,300	1,267,403,665	2,364,090	2,259,127	215,742
Safari 11.1.1	81,548,532	58,206,626	3,230,840	19,856,879	26,420,038	17,854,591	2,735,254	1,791,482	28,424,176	5,169,447	3,094,872	1,309,319	387,983
IE 11.0.0					22,430,695	14,677,008	586,672	548,016	12,904,876	7,702,810	6,155,842	326,736	103,459

	0	n
node@v4.9.1	empty	array
node@v5.12.0	empty	array
node@v6.17.1	empty	array
node@v7.10.1	empty	array
node@v8.16.1	empty	reset
node@v9.11.2	empty	reset
node@v10.16.3	empty	reset
node@v11.15.0	empty	reset
node@v12.10.0	empty	reset
Chrome 40.0.2214	empty	array
Chrome 50.0.2661	empty	array
Chrome 76.0.3809	empty	reset
Firefox 47.0.0	empty	reset
Firefox 69.0.0	empty	reset
Safari 11.1.1	empty	reset
IE 11.0.0	empty	reset