sdk-decode

The decode function takes the return value (response) of a send function and returns the information you probably want, in the formats you probably want.

It understands how to transform cadence values into javascript and allows you to overload those transformations for your own if you want with custom decoders.

Examples

For the following examples these are the imports

import * as fcl from "@onflow/fcl"
import {config} from "@onflow/config"
import {decode} from "@onflow/sdk-decode"

Decode script return value

var v1 = await fcl.send([
  fcl.script`
    pub fun main(): Int {
      return 5 + 6
    }
  `
]).then(decode)

console.assert(v1 === 11)

Cast script return value to application domain type at edge

Somewhere central in your application you can configure the decode function with custom decoders. It only needs to exist once and needs to happen before your script is called.

class Point {
  constructor({x, y}) {
    this.x = x
    this.y = y
  }
}

config()
  .put("decoder.Point", async point => new Point(point))

Then your script can be something like this.

var v2 = await fcl.send([
  fcl.script`
    pub struct Point {
      pub var x: Int
      pub var y: Int

      init(x: Int, y: Int) {
        self.x = x
        self.y = y
      }
    }

    pub fun main(): Point {
      return Point(x: 5, y: 8)
    }
  `
]).then(decode)

console.assert(v2 instanceof Point)
console.assert(v2.x === 5)
console.assert(v2.y === 8)