backported JSVM toString

plugins/jsvm/binds.go

@@ -301,6 +301,34 @@ func baseBinds(vm *goja.Runtime) {
 		return string(bodyBytes), nil
 	})
 
+	vm.Set("toString", func(raw any, maxReaderBytes int) (string, error) {
+		switch v := raw.(type) {
+		case io.Reader:
+			if maxReaderBytes == 0 {
+				maxReaderBytes = rest.DefaultMaxMemory
+			}
+
+			limitReader := io.LimitReader(v, int64(maxReaderBytes))
+
+			bodyBytes, readErr := io.ReadAll(limitReader)
+			if readErr != nil {
+				return "", readErr
+			}
+
+			return string(bodyBytes), nil
+		default:
+			str, err := cast.ToStringE(v)
+			if err == nil {
+				return str, nil
+			}
+
+			// as a last attempt try to json encode the value
+			rawBytes, _ := json.Marshal(raw)
+
+			return string(rawBytes), nil
+		}
+	})
+
 	vm.Set("sleep", func(milliseconds int64) {
 		time.Sleep(time.Duration(milliseconds) * time.Millisecond)
 	})

plugins/jsvm/binds_test.go

@@ -47,7 +47,7 @@ func TestBaseBindsCount(t *testing.T) {
 	vm := goja.New()
 	baseBinds(vm)
 
-	testBindsCount(vm, "this", 17, t)
+	testBindsCount(vm, "this", 18, t)
 }
 
 func TestBaseBindsSleep(t *testing.T) {
@@ -92,6 +92,41 @@ func TestBaseBindsReaderToString(t *testing.T) {
 	}
 }
 
+func TestBaseBindsToString(t *testing.T) {
+	vm := goja.New()
+	baseBinds(vm)
+	vm.Set("scenarios", []struct {
+		Name     string
+		Value    any
+		Expected string
+	}{
+		{"null", nil, ""},
+		{"string", "test", "test"},
+		{"number", -12.4, "-12.4"},
+		{"bool", true, "true"},
+		{"arr", []int{1, 2, 3}, `[1,2,3]`},
+		{"obj", map[string]any{"test": 123}, `{"test":123}`},
+		{"reader", strings.NewReader("test"), "test"},
+		{"struct", struct {
+			Name    string
+			private string
+		}{Name: "123", private: "456"}, `{"Name":"123"}`},
+	})
+
+	_, err := vm.RunString(`
+		for (let s of scenarios) {
+			let result = toString(s.value)
+
+			if (result != s.expected) {
+				throw new Error('[' + s.name + '] Expected string ' + s.expected + ', got ' + result);
+			}
+		}
+	`)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestBaseBindsCookie(t *testing.T) {
 	app, _ := tests.NewTestApp()
 	defer app.Cleanup()

plugins/jsvm/internal/types/types.go

@@ -194,22 +194,34 @@ declare var $app: PocketBase
 declare var $template: template.Registry
 
 /**
- * readerToString reads the content of the specified io.Reader until
+ * This method is superseded by toString.
- * EOF or maxBytes are reached.
  *
- * If maxBytes is not specified it will read up to 32MB.
+ * @deprecated
+ * @group PocketBase
+ */
+declare function readerToString(reader: any, maxBytes?: number): string;
+
+/**
+ * toString stringifies the specified value.
  *
- * Note that after this call the reader can't be used anymore.
+ * Support optional second maxBytes argument to limit the max read bytes
+ * when the value is a io.Reader (default to 32MB).
+ *
+ * Types that don't have explicit string representation are json serialized.
  *
  * Example:
  *
  * ` + "```" + `js
- * const rawBody = readerToString(c.request().body)
+ * // io.Reader
+ * const ex1 = toString(e.request.body)
+ *
+ * // slice of bytes ("hello")
+ * const ex2 = toString([104 101 108 108 111])
  * ` + "```" + `
  *
  * @group PocketBase
  */
-declare function readerToString(reader: any, maxBytes?: number): string;
+declare function toString(val: any, maxBytes?: number): string;
 
 /**
  * sleep pauses the current goroutine for at least the specified user duration (in ms).
@@ -713,7 +725,7 @@ declare namespace $os {
    * const cmd = $os.cmd('ls', '-sl')
    *
    * // execute the command and return its standard output as string
-   * const output = String.fromCharCode(...cmd.output());
+   * const output = toString(cmd.output());
    * ` + "```" + `
    */
   export let cmd: exec.command