jquery - Javascript object sort works only sometimes -

my ajax call returns javascript object sometimes sortable. because literally works , other times not. not know why. when not work this.

uncaught typeerror: cars.sort not function

i have specified return datatype json. console.log(typeof cars) always return object regardless of whether sort works. since inside success statement, safe assume cars loaded everytime therefore not async issue. read answer , decided try [].sort.call(cars).sort(sort_timestamp) not work. lost why cars.sort works , not always. sort_timestamp function sorts timestamp field of car object.

$.ajax({     url: url,      datatype: 'json',     success: function (cars) {         console.log(typeof cars); // prints word 'object'         cars.sort(sort_timestamp);          // tried these well. work         // cars.sort((a, b) => a.timestamp - b.timestamp);         // [].sort.call(cars).sort(sort_timestamp);     } }); 

sort method of array [] , not object {}.

to solve problem have 2 options:

• fix back-end service make sure return array wanted sort

• convert object array

to safely check if variable object cannot use typeof returns object both array , object types

use: object.prototype.tostring.call( thevariableyouwanttobechecked )

$.ajax({     url: url,      datatype: 'json',     success: function (cars) {       // check if cars object       if (object.prototype.tostring.call(cars) == "[object object]")       {         var result = [];         var keys   = object.keys(cars);         // convert array;         (var = 0; < keys.length; i++)         {           var key = keys[i];           result.push(cars[key]);         }          cars = result;          // sort         cars.sort();       }     } }); 

hope helps