Shiny selectizeInput: Read current text - r

Question

With the Shiny selectizeInput widget, the user can type in text as well as select a value from a list of values. Is there a way in R to read the current value of the text?
(Added)
I should make it clear that I want to be able to read the text the user enters before he has made a selection. As zimia points out, after he has made a selection, the value of whatever he selected becomes available as input$input_id (assuming that the selectize input has the id "input_id").

Answer 1

you can just use the input$input_id. See below
ui <- fluidRow(
selectizeInput("input1","Enter Text",choices=c("A","B") ,options = list(create=TRUE)),
textOutput("output1")
)
server<- function(input, output, session){
output$output1 <- renderText({
req(input$input1)
input$input1
})
}

Answer 2

Shiny's selectizeInput still gives access to the internal properties, methods and callbacks of Selectize.js through "options" argument of updateSelectizeInput. Selectize.js exposes callback "onType", so you can use like that:
updateSelectizeInput(
session,
'input1',
options = list(
onType = I('
text => Shiny.setInputValue("input1_searchText", text)
'),
onBlur = I('
() => Shiny.setInputValue("input1_searchText", null)
')
)
)
and consume it with observer:
observeEvent(input$input1_searchText, {
print(input$input1_searchText)
}, ignoreNULL = FALSE
)
Please, note, that I was also interested to know when the select looses focus and hence used "onBlur" event to set the search text to NULL.

Answer 3

I was thinking that there would be a solution at the level of R/shiny. But I have found a solution that uses javascript.
library(shiny)
js <- '
$(document).on("keyup", function(e) {
minChars = 4;
tag1 = document.activeElement.getAttribute("id");
val1 = document.activeElement.value;
if (tag1 == "input1-selectized") {
if (Math.sign(val1.length +1 - minChars) == 1) {
obj = { "val": val1 };
Shiny.onInputChange("valueEntered", obj);
}
}
});
'
ui <- fluidRow(
tags$script(js),
selectizeInput(
"input1",
"Enter text",
choices = c("A", "B"),
options = list(create = FALSE)),
textOutput("output1")
)
server <- function(input, output, session) {
output$output1 <- renderText({
req(input$valueEntered$val)
input$valueEntered$val
})
}
shinyApp(ui = ui, server = server)
The javascript looks for text entered into the element with id "input1-selectized", and if the value is length 4 or more, sets the shiny variable "valueEntered" to an object with val = the text.
Then the observeEvent uses the shiny variable input$valueEntered to set the output text.
The reason in the javascript for using the Math.sign function rather than >, and the reason for nested if's is because for some reason, Shiny replaces infix operators such as > and && by their html equivalents, > and &&.
Note that if the selectizeInput widget has id "input1", then the corresponding text field has id "input1-selectized".