在AJAX上发送var的正确方法是什么

Question

I have a javascript function that calls a Webmethod. I tried sending a regular string to the webmethod and it works. On var empid= $('#' + txtId).val() Im getting the right value of the text box. What is the right way of sending empid over ajax ? I have tried a few thing and they dont work. Any help would be appreciated. Thanks

.js

function toggle(txtId, lblname, txtcode) {

var empid = $('#' + txtId ).val();

$.ajax({
    type: "POST",
    url: "SearchEmpId.asmx/GetEmployeeName",
    data: '{ id: empid }',
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function (data) {
        $('#' + lblname).html(data.d);

    }
});    
}

.asmx.vb (webmethod)

Public Function GetEmployeeName(ByVal id As String) As String

Return "It works"

End Function

This is a screen shoot when removing contentType

Answer 1

Instead of

data: '{ id: empid }',

use

data: { id: empid },

Its sending JSON

Answer 2

Use dataType:"json" for json data

$.ajax({
     url: 'ajax.php', //This is the current doc
     type: "POST",
     dataType:'json', // add json datatype to get json
     data: ({name: 145}),
     success: function(data){
         console.log(data);
     }
}); 

Read Docs http://api.jquery.com/jQuery.ajax/

Also in PHP

<?php
  $userAnswer = $_POST['name']; 
  $sql="SELECT * FROM <tablname> where color='".$userAnswer."'" ;
  $result=mysql_query($sql);
  $row=mysql_fetch_array($result);
  // for first row only and suppose table having data
  echo json_encode($row);  // pass array in json_encode  
?>

Answer 3

You can use like below:

var empid=$('#txtEmpId').val();

Pass empid in data as

data: { id: empid },

Check out the fiddle here: http://jsfiddle.net/gN6CT/103/