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onflow.org
Flow Playground

Execute Scripts

How to execute scripts

It is often the case that you need to query the current state of the network. For example, to check balance of an account, read public values of a contract or ensure that a user has a specific resource in their storage. We abstract this interaction into a single method called executeScript. Method have 2 different signatures.

⚠️ Required: Your project must follow the required structure it must be initialized to use the following functions.

executeScript(props)

Provides explicit control over how you pass values.

Arguments

props object accepts following fields:

NameTypeOptionalDescription
codestring✅string representation of Cadence script
namestring✅name of the file in scripts folder to use (sans .cdc extension)
args[Any]✅an array of arguments to pass to script. Optional if script does not expect any arguments.

⚠️ Required: Either code or name field shall be specified. Method will throw an error if both of them are empty. If name field provided, framework will source code from file and override value passed via code field.

Usage

import path from "path"
import {init, emulator, executeScript} from "@onflow/flow-js-testing"

const main = async () => {
  const basePath = path.resolve(__dirname, "../cadence")

  // Init framework
  init(basePath)
  // Start emulator
  await emulator.start()

  // Define code and arguments we want to pass
  const code = `
    pub fun main(message: String): Int{
      log(message)

      return 42
    }
  `
  const args = ["Hello, from Cadence"]

  const [result, e] = await executeScript({code, args})
  console.log(result, e)

  // Stop emulator instance
  await emulator.stop()
}

main()

executeScript(name: string, args: [any])

This signature provides simplified way of executing a script, since most of the time you will utilize existing Cadence files.

Arguments

NameTypeOptionalDescription
namestringname of the file in scripts folder to use (sans .cdc extension)
args[Any]✅an array of arguments to pass to script. Optional if scripts don't expect any arguments. Default: []

Usage

import path from "path"
import {init, emulator, executeScript} from "@onflow/flow-js-testing"

const main = async () => {
  const basePath = path.resolve(__dirname, "../cadence")

  // Init framework
  init(basePath)
  // Start emulator
  await emulator.start()

  // Define arguments we want to pass
  const args = ["Hello, from Cadence"]

  const [result, error] = await executeScript("log-message", args)
  console.log(result, error)

  await emulator.stop()
}

main()

📣 Note about method usage