Get all Attributes from a HTML element with Javascript/jQuery

If you just want the DOM attributes, it's probably simpler to use the attributes node list on the element itself:

var el = document.getElementById("someId");
for (var i = 0, atts = el.attributes, n = atts.length, arr = []; i < n; i++){
    arr.push(atts[i].nodeName);
}

Note that this fills the array only with attribute names. If you need the attribute value, you can use the nodeValue property:

var nodes=[], values=[];
for (var att, i = 0, atts = el.attributes, n = atts.length; i < n; i++){
    att = atts[i];
    nodes.push(att.nodeName);
    values.push(att.nodeValue);
}

You can use this simple plugin as $('#some_id').getAttributes();

(function($) {
    $.fn.getAttributes = function() {
        var attributes = {}; 

        if( this.length ) {
            $.each( this[0].attributes, function( index, attr ) {
                attributes[ attr.name ] = attr.value;
            } ); 
        }

        return attributes;
    };
})(jQuery);

Simple:

var element = $("span[name='test']");
$(element[0].attributes).each(function() {
console.log(this.nodeName+':'+this.nodeValue);});

Because in IE7 elem.attributes lists all possible attributes, not only the present ones, we have to test the attribute value. This plugin works in all major browsers:

(function($) {
    $.fn.getAttributes = function () {
        var elem = this, 
            attr = {};

        if(elem && elem.length) $.each(elem.get(0).attributes, function(v,n) { 
            n = n.nodeName||n.name;
            v = elem.attr(n); // relay on $.fn.attr, it makes some filtering and checks
            if(v != undefined && v !== false) attr[n] = v
        })

        return attr
    }
})(jQuery);

Usage:

var attribs = $('#some_id').getAttributes();

Setter and Getter!

(function($) {
    // Attrs
    $.fn.attrs = function(attrs) {
        var t = $(this);
        if (attrs) {
            // Set attributes
            t.each(function(i, e) {
                var j = $(e);
                for (var attr in attrs) {
                    j.attr(attr, attrs[attr]);
                }
            });
            return t;
        } else {
            // Get attributes
            var a = {},
                r = t.get(0);
            if (r) {
                r = r.attributes;
                for (var i in r) {
                    var p = r[i];
                    if (typeof p.nodeValue !== 'undefined') a[p.nodeName] = p.nodeValue;
                }
            }
            return a;
        }
    };
})(jQuery);

Use:

// Setter
$('#element').attrs({
    'name' : 'newName',
    'id' : 'newId',
    'readonly': true
});

// Getter
var attrs = $('#element').attrs();