how to improve jquery's performance or use regular replace?

I'd like 开发者_如何学Goto add prefix id to all DOM element's several attributes.

what is the best way ?

I found jquery's find and each function is slow. should I use regular replace ?

jquery's code for example:

$("body").find("id").each(function(){
    $(this).attr("id", "AAA_" + $(this).attr("id"));
});

$("body").find("label[for]").each(function(){
    $(this).attr("for", "AAA_" + $(this).attr("for"));
});

First, you're looking for id elements, not elements with an id attribute. Use [id] instead.

Second, use the callback argument to attr:

$('[id]').attr('id', function(idx, oldId) {
    return 'AAA_' + oldId;
});
$('label[for]').attr('for', function(idx, oldFor) {
    return 'AAA_' + oldFor;
});

Do you really want to modify HTML attribute values, or do you want to modify DOM properties? I suspect that you actually want to deal with DOM properties.

The following will add a prefix to nominated DOM properties if that property has a value other than empty string. Be careful, some properties are boolean, adding a string prefix may have unusual results.

I'd be interested to know how much faster this is than jQuery.

function prefixProperty(prop, prefix) {
  var el, els = document.getElementsByTagName('*');
  var i = els.length;

  while (i--) {
    el = els[i];

    // Only modify property if it has a value other than empty string
    if (el[prop].length) {
      el[prop] = prefix + el[prop];
    }
  }
}

I would change your selector to (i assume only imputs) and do it all in one loop

$('input').each(function(){
    var cur_id = this.id;
    $('label[for:="'+cur_id +'"]').attr('for',"AAA_" + cur_id  );
    cur_id  = "AAA_" + cur_id ;
});