Question

I need to get the value of textbox as I type, and perform a function of JSON, I tried doing this:

$(document).ready(function () {
  $("#<%= txtBusca.ClientID %>").keypress(function () {
    $.ajax({
      type: "POST",
      data: "{ 'valor' : '" + $(this).val() + "'}",
      url: "Especialidades.aspx/Buscar",
      contentType: "application/json; charset=utf-8",
      dataType: "json",
      success: function () {
        alert('OK');
      }
    })
   });
});

But it doesn’t work.

Answer 1

I think the line below is causing the problem

data: "{ 'valor' : '" + $(this).val() + "'}",

The reason is this keyword. In your code it is referring ajax context.

I recommend you to assign this into variable before Ajax call blocks and refer it inside like the following :

$("#<%= txtBusca.ClientID %>").keypress(function () {

var enteredValue=$(this).val();

$.ajax({
  type: "POST",
  data: { 'valor' : enteredValue },