ajax return javascript to php

Your current code is correct, and the value for $_POST['tz'] is being correctly passed to PHP because the response is displaying in the web inspector.

Your problem is not with WordPress, but with jQuery: once you echo $_POST['tz'], that is available to jQuery for use, but you have to tell jQuery how to display that information somewhere on your page.

Example 1
Alert your response from the ajax call.

jQuery.ajax({
    type: 'post',
    url: '/wp-admin/admin-ajax.php',
    data:{
        'action':'get_tz',
        'tz':timezone.name()
    },
    dataType: 'html',
    success:function(data){
        alert(data);
    },
    error: function(errorThrown){
        alert('error');
        console.log(errorThrown);
    }
});

Example 2
Load the response into an element with ID “response”.

jQuery.ajax({
    type: 'post',
    url: '/wp-admin/admin-ajax.php',
    data:{
        'action':'get_tz',
        'tz':timezone.name()
    },
    dataType: 'html',
    success:function(data){
        jQuery('#response').html( data );
    },
    error: function(errorThrown){
        alert('error');
        console.log(errorThrown);
    }
});

Example 3
Use jQuery.load instead of jQuery.ajax() for simpler loading into an HTML element with ID response.

jQuery('#response').load( '/wp-admin/admin-ajax.php', {
    'action':'get_tz',
    'tz':timezone.name()
});

Thanks for the advise I can get your examples to work but what I think I am looking for is a way to set a cookie then use php to read that cookie I got this to work with

jQuery.ajax({
	type: 'post',
	url: '/wp-admin/admin-ajax.php',
	data:{
		'action':'get_tz',
		'tz':timezone.name()
	},
	dataType: 'html',
	success:function(data){
		document.cookie = "timezone=" + data;
    },
	error: function(errorThrown){
		alert('error');
		console.log(errorThrown);
	}
});

but what happens on the first load is the cookie is set and it shows on a reload is there a way to set this cookie before the page loads. The variable I am looking to set as a cookie is timezone by name. Then is php I will be able to do a time comparison and display content accordingly. I was also wondering if ajax is nessecary to set this cookie value. Thanks for any help.

It is not possible to set a cookie via javascript before a page loads, but you can follow my original examples and use jQuery to modify your page content without reloading the page.

AJAX is not neccissary to set a cookie, but it is required for sending information about your client’s timezone from Javascript without reloading. You can achieve client timezone detection with no javascript or AJAX (before loading) by using a PHP Geolocation library, such as geoPlugin.

For another Javascript example, take a look at the article linked to in answer #1 of this StackOverflow thread, as well as the full example given in answer #2.

This question isn’t really related to WordPress in any way at this point. You may be best served in jQuery-related forums.

I have the same TYPE of problem where I have JS variables that I need to send along with my AJAX

data = {
	action:'wpa56343_search',
	latitude: $('input#latitude').attr('value'),
	longitude: $('input#longitude').attr('value')
 };
    	_do_ajax(data);
}); // end init func

    	function _do_ajax(obj) {
    	console.log(obj);
        $.ajax({
            type:"POST",
            url: My_Obj.ajaxurl,
            data: data,
            dataType: 'json',
            success: function( response ){ loop with query data }

This work, but I cannot get $_POST[] variables out of it on the PHP side to include in my query…