[devote]

<form id="myForm">
    <input name="test" value="blabla" />
    <textarea name="area">Тестовый текст</textarea>
</form>
<script type="text/javascript">
function serializeForm( form ) {

	var result = '', gE = 'getElementsByTagName',
		inputs = [ form[ gE ]('input'), form[ gE ]('select'), form[ gE ]('textarea'), form[ gE ]('button') ],
		iln = inputs.length, eln, i, j, name;

	for( i = 0; i < iln; i++ ) {

		eln = inputs[ i ].length;

		for( j = 0; j < eln; j++ ) {
			if ( inputs[ i ][ j ] ) {
				if ( name = inputs[ i ][ j ].getAttribute( 'name' ) ) {
					result += escape( name ).replace( /\+/g, '%2B' );
					result += '=' + escape( inputs[ i ][ j ].value ).replace( /\+/g, '%2B' ) + '&';
				}
			}
		}
	}

	return result;
}

alert( serializeForm( document.getElementById('myForm') ) );
</script>