How can I use js.Value as argument to js.Global().Get-CodePudding

Trying with GO WebAssembly accessing the browser IndexedDB, with the below code I was able to create the ibdexedDB, but I got an error while trying to access it using js.Global().Get(dbx) or even trying to access this.result

//go:build js && wasm

package main

import (
    "fmt"
    "syscall/js"
)

var dbOk, dbErr js.Func
var db js.Value

func main() {
    fmt.Println("Hello WASM")
    db = js.Global().Get("indexedDB").Call("open", "Database", 1)

    dbOk = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
        defer dbOk.Release()
/* Here I've an error */
        dbx := this.result
        fmt.Println("this is: ", dbx)
/**********************/
        js.Global().Call("alert", "ok.")
        return nil
    })
    db.Set("onsuccess", dbOk)

    dbErr = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
        defer dbErr.Release()

        js.Global().Call("alert", "sorry.")
        return nil
    })
    db.Set("onerror", dbErr)
    
    /* This line is wrong, can not access `db` */
    js.Global().Get(dbx).Call("transaction", "readwrite").Call("objectStore", "employee").Call("add", `{ id: "00-01", name: "Karam", age: 19, email: "[email protected]" }`)

    c := make(chan int)
    <-c
}

The error I got is:

# command-line-arguments
./wasm.go:21:14: this.result undefined (type js.Value has no field or method result)
./wasm.go:41:17: cannot use dbx (type js.Value) as type string in argument to js.Global().Get

To map it with JavaScript, I wanted this go:

    dbOk = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
        defer dbOk.Release()
        dbx := this.result
        fmt.Println("this is: ", dbx)
        js.Global().Call("alert", "ok.")
        return nil
    })
    db.Set("onsuccess", dbOk)

To be equivalent to this JavaScript:

var dbx

request.onsuccess = function(event) {
    dbx = request.result;
    console.log("success: "  dbx);
};

And this go code:

js.Global().Get(dbx).Call("transaction", "readwrite").Call("objectStore", "employee").Call("add", `{ id: "00-03", name: "Karam", age: 19, email: "[email protected]" }`)

To replace this JavaScript code:

dbx.transaction(["employee"], "readwrite")
    .objectStore("employee")
    .add({ id: "00-03", name: "Karam", age: 19, email: "[email protected]" });

CodePudding user response：

In this context, this is a Javascript object, so you have to get the property result of it:

result:=this.Get("result")

The result will be a js.Value, and you can get the the Go value of it if it is a primitive, or descend to further object elements using result.Get(), or Call a method of it.