l1

Game utility: Trigger a function after a set amount of game updates.

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✨ Features

This library is like setTimeout and setInterval controlled by updates from a game loop.

This way, if you want to something to happen in your game after 60 updates, you just have to write:

await delay(60)
transitionToNextScreen()

In order for this to work, you need to call update on every update. If you are using PixiJS this would mean that somewhere in your code you have to write:

ticker.add(update)

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API

• delay(duration, options) - Wait a set duration of game updates

await delay(60)
// Do something once after 60 game updates

• forever(callback, interval, options) - Call a function forever, each interval game update

const interval = 60
forever(() => {
  // Do something forever each 60 game updates
}, interval)

• every(callback, duration, options) - Call a function every update until duration is reached

const duration = 60
await l1.every(() => {
  // Do something every game update until 60 game updates have passed
}, duration)

• update(deltaTime) - Needs to be called on every game update

Utils

• getAll() - Get all behaviors

• get(id) - Get one behavior by id

• getByLabel(label) - Get a list of behaviors with a label

• cancel(behavior) - Takes an id or behavior object. Marks the behavior for cancellation. Will be cancelled after all behaviors have been processed in the current game update.

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Start by calling createInstance.

const { update, delay } = createInstance()

// Call update every game update
ticker.add(update)
await delay(60)

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📦 Install

npm install l1

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Getting started - once

TODO: Better examples

import * as l1 from 'l1'
import * as PIXI from 'pixi.js'

const app = new PIXI.Application()

document.body.appendChild(app.view)

app.ticker.add(l1.update)

app.loader.load(() => {
  const square = new PIXI.Sprite(texture)
  app.stage.addChild(square)

  // Move 1 pixel every 3 ticks
  const move = l1.repeat(
    () => {
      square.x += 1
      if (square.x > 500) {
        l1.cancel('move')
      }
    },
    3,
    { id: 'move' },
  )
})

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Recipes

Deleting behaviors

cancel just marks the behavior for cancellation, but it won't actually be cancelled until the next update

Therefore, you might need to wait a game update before you continue:

const gameOver = () => {
  cancel('gameLoop')
  // Ensures that the game doesn't continue until the `gameLoop` behavior has been deleted
  await delay(1)
  // Continue
}

Log update duration

Use performance.now

import * as l1 from 'l1'

app.ticker.add((deltaTime) => {
  const before = performance.now()

  l1.update(deltaTime)

  const after = performance.now()
  const delta = after - before
})

Log update duration averages

Catch errors

Wrap l1.update with a try catch

import * as l1 from 'l1'

app.ticker.add((deltaTime) => {
  try {
    l1.update(deltaTime)
  } catch (error) {
    console.error(error)
    logToExternalService(error)
  }
})

Use delay in a loop

Use a for..of loop

for (const item of list) {
  doStuff(item)
  await delay(50)
}