How to pass parameter to UserData in AWS template

For instance, you have a parameter in the template:

"EnableWebServer": {
            "Default": "No",
            "Description": "Enable Web Server in the Ubuntu or not",
            "Type": "String"
 }

You want to pass it to the Shell Scripts in UserData to run some commands based on this parameter. Here is an sample:

"UserData": {
                    "Fn::Base64": {
                        "Fn::Join": [
                            "",
                            [
                                "#!/bin/bash -xe\n",
                                "if [[ \"Yes\" == ",
                                {
                                    "Ref": "EnableWebServer"
                                },
                                " ]]; then ",
                                "echo yes > /tmp/1.txt; ",
                                "else ",
                                "echo no > /tmp/1.txt;",
                                "fi\n",
                            ]
                        ]
                    }
                }