如何从R Shiny中获取JavaScript的屏幕分辨率？ [英] How to get screen resolution from JavaScript in R Shiny?

问题描述

我想从JavaScript中获取屏幕分辨率，存储在Shiny Server上的 GetScreenWidth 变量中。

I want to get screen resolution from JavaScript, stored in the GetScreenWidth variable on Shiny Server.

I尝试了参考：

1. 从server.R中的.js接收数据闪亮


2. https://ryouready.wordpress.com/2013/ 11/20 / send-data-from-client-to-server-and-back-using-shiny /

1. Receiving data from .js in server.R shiny
2. https://ryouready.wordpress.com/2013/11/20/sending-data-from-client-to-server-and-back-using-shiny/

所以我有：

ui.R

shinyUI(
  bootstrapPage(

    verbatimTextOutput("results")
    ,tags$script('
        var jsWidth = screen.width;
        Shiny.onInputChange("GetScreenWidth",jsWidth);
    ')
   )
 )

server.R

 shinyServer(function(input,output){

     output$results=renderPrint({
     input$GetScreenWidth
   })

 })

它将返回 NULL by verbatimTextOutput 。

我应该如何修改代码？谢谢！

How should I modify the code? Thanks!

推荐答案

问题是你在Shiny初始化之前运行JavaScript代码。您可以使用新功能，告诉您何时闪亮准备就绪，这里的示例代码

The problem is that you're running the JavaScript code before Shiny is initialized. You can use the new feature that tells you when shiny is ready, here's example code

jscode <-
'$(document).on("shiny:connected", function(e) {
  var jsWidth = screen.width;
  Shiny.onInputChange("GetScreenWidth",jsWidth);
});
'

library(shiny)
runApp(shinyApp(
  ui = fluidPage(
    tags$script(jscode)
  ),
  server = function(input, output, session) {
    observe({
      cat(input$GetScreenWidth)
    })
  }
))

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