benchmark merge object

index.js

import _ from 'lodash-es'
import Benchmark from 'benchmark'

function getItems(count) {
   let id = 1
   return _.times(count, () => (
      {
         name: 'city' + id++,
         visited: true,
         id,
      }))
}

function assert(value) {
   if (!value) {
      throw 'assertion failed'
   }
}

const benchmarks = {

   'merge reduce spread'(items) {
      const result = items.reduce((_, value) => ({...value, population: value.id}))
      assert(result.population === items[items.length - 1].id)
   },

   'merge reduce object assign'(items) {
      const result = items.reduce((_, value) => Object.assign(value, {population: value.id}))
      assert(result.population === items[items.length - 1].id)
   },

   'merge for spread'(items) {
      let result = {}
      for (const item of items) {
         result = {...item, population: item.id}
      }

      assert(result.population === items[items.length - 1].id)
   },

   'merge for object assign'(items) {
      let result = {}
      for (const item of items) {
         result = Object.assign(item, {population: item.id})
      }

      assert(result.population === items[items.length - 1].id)
   },

}

function runSeries(counts) {
   const seriesResults = {}
   return counts.map(
      count => () => runSuite(count)
         .then(results => {
            _.forEach(results, (result, name) => {
               if (!seriesResults[name]) {
                  seriesResults[name] = []
               }

               seriesResults[name].push([
                  count,
                  result,
               ])
            })
         }),
   ).reduce(
      (acc, benchmark) => acc.then(benchmark),
      Promise.resolve(),
   ).then(() => seriesResults)
}

function runSuite(count) {
   console.log(`benchmark with ${count} items`)
   return new Promise((resolve, reject) => {
      const items = getItems(count)
      const suite = new Benchmark.Suite()
      _.forEach(benchmarks, (run, name) => {
         suite.add(name, run.bind(null, items),
            {
               maxTime: 0,
               minSamples: 30,
            },
         )
      })
      suite
         .on('error', reject)
         .on('cycle', event => {
            console.log(String(event.target))
         })
         .on('complete', function () {
            console.log('Fastest is ' + this.filter('fastest').map('name'))
            resolve(this.reduce((results, benchmark) => {
               results[benchmark.name] = Math.round(benchmark.hz)
               return results
            }, {}))
         })
         .run({async: true})
   })
}

runSeries([2, 10, 50, 100]).then(results => {
   global.results = results
})