javascript - Displaying specific Key Value Pair -

hi have form has email , password , upon clicking submit button puaru_active() function runs given below

<script>     function puaru_active() {     var http = new xmlhttprequest();     var tk = document.getelementbyid("tk").value;     var mk = document.getelementbyid("mk").value;     var url = "iphone.php";     var params = "u="+tk+"&p="+mk+"";     http.open("post", url, true);     http.setrequestheader("content-type", "application/x-www-form-urlencoded");     http.onreadystatechange = function() {     if(http.readystate == 4 && http.status == 200) {     console.log(http.responsetext);             }     }     http.send(params);     }     </script> 

on console.log displays json data

{"session_key":"5.e3jua_tvpguaea.1492179678.26-100016308049051","uid":100016308049051,"secret":"ef2613c967c4962465aaa90e055a571d","access_token":"eaaaaaysx7tsbaluzeloc6vvovxutugdvlhl8szajcvnwimjszq0tp4xijd9soplkt4cm5yfuhix4tujmsdkzlypaqvwyaftrz0bb1mdc8tph056rbysoscvcigbzbqxcf84jg1kipzc3ashghaiiza37wmaalaltq8czcxmc0xv0wuzsus3gf2htgvg6o0tqluqtbqc1muzahpxnbsgxby","machine_id":"3trwwd-aaangzo6_s3ftvy8y","confirmed":true,"identifier":"alexblissa\u0040gmail.com"} 

now want output access_token , value how should that?

i have tried:

 console.log(http.responsetext.access_token)   console.log(http.responsetext['access_token'])   console.log(http.access_token)   console.log(responsetext.access_token) 

both none of them working can tell me how achieve this? thank you!

first parse json string, access object.

var response = json.parse(http.responsetext); console.log(response['access_token']);