Question : How can I use the result of a promise from JS to Mint (in the context of Webview) ?

[serge-hulne]

In the snippet hereunder, a function f() (defined in Webview) is called via javaScript (using the "back-ticks" method).

It works, but I was wondering how to pass the value returned by f() into a variable in the context of Mint.

More precisely, I wanted to pass the value : value["m"] into the variable a hereunder:

component Main {

  state val : String = "initial state"

  fun modify() : Promise(Never, Void){
    try {
      a = "Modified" 
      `f().then(value => {
            console.log(value["m"])
             a = value["m"]
      })`
      next { val = a } 
    }
  }

  fun render : Html {
    <div>
        <button onClick={modify}>
          "Click Me!"
        </button>
        <text>
          <{val}>
        </text>
    </div>
  }

}

[gdotdesign]

Hi 👋

Couple of things to make this work:

• use sequence instead of try - this will make it asynchronous, and it will unwrap Promise(error, value)
• just return the value in the promise and assign it to a variable

So this in theory should work:

component Main {
  state val : String = "initial state"

  fun modify() : Promise(Never, Void){
    sequence {
      value = 
       `f().then(value => value["m"])`

      next { val = value } 
    }
  }

  fun render : Html {
    <div>
        <button onClick={modify}>
          "Click Me!"
        </button>
        <text>
          <{val}>
        </text>
    </div>
  }
}

[serge-hulne]

Thank you very much!