如何在Elm中获取svg文本的长度

import Svg exposing (svg, text)
import Svg.Attributes exposing (width, height)

svg [ width "500px", height "200px" ]
    [ text [ ] "Hello, SVG!" ]

import Html exposing (Html)
import Html exposing (div)
import Html exposing (program)

view : Html msg
view =
    div []
        [ svg [ width "500px", height "200px" ]
            [ text [ ] "Hello, SVG!" ]
        ]

main =
    program { view = view, init = init, update = update, subscriptions = subscriptions }