Question

I want to know the differences between:

$('a').map(function(){return this})
$.map($('a'), function(){return this})

They behave differently when I test them in firebug console.

Answer 1

Having just briefly tested, they do perform differently. ‘this’ in the context of the latter references the window object. However you do have access the current element when looping through the object/array passed in:

$('a').map(function(){
    return this
});
$.map($('a'), function(el){
    return el;
});

The latter is typically used for non-jQuery objects and arrays, whereas the former is for this purpose.

See the documentation for more information:

http://api.jquery.com/map/

http://api.jquery.com/jQuery.map/