Arrow functions create a new function on every render, decreasing performance as a result of:
This is particularly evident when iterating over an array to generate components, which also need function props to handle state change as a result of user interaction, such as onClick/onPress.
| // @flow | |
| type Predicate<T> = T => boolean | |
| export default function cherryPick<T>(memo: Array<T>, predicate: Predicate<T>, subject: T): Array<T> { | |
| if (predicate(subject)) { | |
| return [ ...memo, subject ] | |
| } | |
| if (Array.isArray(subject)) { | |
| return subject.reduce((memo, subject) => cherryPick(memo, predicate, subject), memo) |
| class Foo { | |
| set foo(value) { | |
| Object.defineProperty(this, '_foo', { | |
| value: value, | |
| enumerable: false | |
| }) | |
| } | |
| get foo() { |
| /* @flow */ | |
| type KeyType = string | |
| type ValueType = any | |
| type MyMap = { | |
| [KeyType]: ValueType | |
| } | |
| const object: MyMap = { |
| select STR_TO_DATE(CONCAT(H.date, ' ', H.time), '%d/%m/%Y %H:%i') as datetime, H.min, H.max, coalesce(S.steps,0) as steps from heartrate H | |
| left join steps S on | |
| (H.date = S.date or H.date is null and S.date is null) | |
| and | |
| (H.time = S.time or H.time is null and S.time is null) | |
| order by H.date, H.time |
| fs.createReadStream(argv.heart) | |
| .pipe(csv.parse({ objectMode: true })) | |
| .pipe(csv.transform({ | |
| header: columns => { | |
| const properties = { | |
| Start: 'start', | |
| End: 'end', | |
| 'Heart Rate (count/min)': 'heartRate', | |
| } | |
| return columns.map(column => properties[column] || column) |
| // | |
| // This demonstrates how to use sheet(item:...) when the requirement is to pass a binding to the | |
| // view presented by the sheet. Also relevant to fullCoverSheet(item:...) | |
| // | |
| // What we want the sheet to do is provide an editable form that can be cancelled, so partial changes | |
| // are not committed to the ancestors view state. We only want the state changed IF the form is confirmed (save action) | |
| // | |
| import SwiftUI |
| const common = require('./cucumberjs_formatter_common.js') | |
| const formatter = function (options) { | |
| const cucumber = require(options.parsedArgvOptions.cucumberLibPath) | |
| new cucumber.SummaryFormatter(options) | |
| let currentUri = '' | |
| let currentFeatureName = '' |
| /** | |
| * American Soundex algorithm (see https://en.wikipedia.org/wiki/Soundex) | |
| * | |
| * @example | |
| * americanSoundex('Robert') === 'R163' | |
| * americanSoundex('Rupert') === 'R163' | |
| * americanSoundex('Rubin') === 'R150' | |
| * americanSoundex('Ashcraft') === 'A261' | |
| * americanSoundex('Ashcroft') === 'A261' | |
| * americanSoundex('Tymczak') === 'T522' |
| import { ScheduleTargetBase, ScheduleTargetBaseProps } from "@aws-cdk/aws-scheduler-targets-alpha" | |
| import { IRole, Role } from "aws-cdk-lib/aws-iam" | |
| import { EventBus } from "aws-cdk-lib/aws-events" | |
| import { ISchedule, ScheduleTargetConfig, ScheduleTargetInput } from "@aws-cdk/aws-scheduler-alpha" | |
| /** | |
| * This is a simple implementation of a EventBridge Scheduler Target that will put events to an EventBus. | |
| * It is built upon the base provided by @aws-cdk/aws-scheduler-targets-alpha. | |
| */ |