Can't pass a value from jquery to php - php

Question

What is wrong:
$('#click01').click(function(){
$a = 14;
$.ajax({
url : 'msg.php',
type : 'post',
data : {a:$a}
});
window.location = 'msg.php';
});
msg.php contains:
var_dump($_POST['a']); // NULL, but expected: 14

Answer 1

$('#click01').click(function(){
var a = 14;//not $a since this is javascript
$.ajax({
url : 'msg.php',
type : 'post',
data : {'a':a}
});
window.location = 'msg.php';
});

Answer 2

$('#click01').click(function(){
var a = 14
$.ajax({
type: "POST",
url: "msg.php",
data: {a:a},
beforeSend: function () {
// do action
},
success: function(html){
window.location = 'msg.php';
}
});
});

Answer 3

Rather than set the window.location you want to set a 'success' function on the ajax call so that when it finishes it takes the response and puts it into your page.
E.g. something like:
$('#click01').click(function(){
$a = 14;
$.ajax({
url : 'msg.php',
type : 'post',
data : {a:$a},
success: function(data, textStatus, jqXHR) {
$('#placeToPutTheResponse').append( data );
}
});
});
The above assumes that you have added an HTML node with the id="placeToPutTheResponse"
It is worth reading this other post on SO for a decent overview: jQuery Ajax POST example with PHP
It uses done rather than success, and slightly different syntax, but it's a great overview.

Answer 4

$(document).on('click','#click01',function () {
var a = 14;
$.ajax({
url: 'msg.php',
type: 'post',
data: {a: a},
success: function(e){
console.log(e);
},
error: function(e) {
console.log(e);
}
});
});

Answer 5

Try this
$('#click01').click(function(){
var a = 14;
$.ajax({
url : 'msg.php',
type : 'POST',
data : {a:a},
complete: function (data) {
console.log( data ); // this will tell you the output of var_dump.
window.location.href = 'msg.php';
}
});
// window.location = 'msg.php';
});
also this line window.location.href = 'msg.php'; in function complete will actually redirect you to the msg.php, so if you dont want any redirects remove those lines..