Question

if I write:

var source = new Array();
function doSomething(a){
   chrome.bookmarks.search(a,function(items){
      for(var i = 0;i<items.length;i++)
      {
          source[i] = items[i];

      }

   });
   console.log(source[0].title);
   alert(source[0].title);

}

in the console I can see the values,but what alerted is “undefined”.

can someone tell me why and how to write to get the values?

Answer 1

You are executing alert in the wrong scope – you should do this in the callback function. Try this:

function doSomething(a){
   chrome.bookmarks.search(a,function(items){
      var source = [];
      for(var i = 0;i<items.length;i++)
      {
          source[i] = items[i];

      }
      console.log(source[0].title);
      alert(source[0].title);   
      doSomethingWithResult(source); 
   });      

}

You have seen the right value in the console because it shows reference to the value which have been already filled in this moment (in the callback function).