findObject.js

var list=Array();
list.push({id:1,name:'sohel'});
list.push({id:2,name:'kahled'});
list.push({id:3,name:'Rayan'});
list.push({id:4,name:'John'});

var exist=$.grep(list, function(obj) {
  return obj.name === 'sohel'; 
});

if(exist.length===0){
  //do something
}