jquery - After adding callback function, why is my variable modified inside it unaltered? -


i know asynchronicity, have followed steps of adding callback function why variable unaltered after modify inside of function? - asynchronous code reference but can access changes inside callback function. here code snippet. please help

function callback(point) {         (i = 0; < point.length; i++) {            mydate[i] = point[i].date_time;            myvalue[i] = point[i].my_value;        }         (j = 0; j < mydate.length; j++) {            var temp = new array(mydate[j], myvalue[j]);            myseries[j] = temp;        }        alert("myseries in scope:  " + myseries); //defined     }    alert("myseries out scope:  " + myseries); // undefined    getallmessagesforchart(callback);     function getallmessagesforchart(callback) {                 var data = @html.raw(jsonconvert.serializeobject(this.model))           $.ajax({             url: '/messages/getmessagesforchat',             data: {                 id: data.id,             },             contenttype: 'application/html ; charset:utf-8',             type: 'get',             datatype: 'json'          }).success(function (data) {             callback(data);         }).error(function (e) {             alert("error " + e)         })          }

i hope helps clear things you--

it not issue of scope. matter of order statements executed. if order amazon.com, go front stoop , expect find package? no, have wait drone there.

the myseries variable global variable. not "out of scope" outside callback() function. , it's not can't access changes outside callback() function; it's can't access changes before have been made. alert "myseries out scope" appears in code after callback() function defined, executed before callback() function executed.

even if change order of following 2 statements, alert still executed before callback function, because callback function not executed until ajax call returns, assynchronously.

getallmessagesforchart(callback); alert("myseries out scope:  " + myseries); // undefined

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