$('#keywords').tagsInput({
    'height':'auto',
    'width':'350px',
    'defaultText':'',
    'delimiter': '|'
});
/*The delimiter option above overrides the default comma delimiter in the plugin allowing commas in tags if you prefer that...*/

var $keywords = $("#keywords").siblings(".tagsinput").children(".tag");
var tags = [];
for (var i = $keywords.length; i--;) {
    tags.push($($keywords[i]).text().substring(0, $($keywords[i]).text().length -  1).trim());
}

/*Then if you only want the unique tags entered:*/
var uniqueTags = $.unique(tags);
alert(uniqueTags.toSource());

$("#btn").click(function () {
         var $tagWord = $("#tags_2").siblings(".tagsinput").children(".tag");
         var tags = [];
         for (var i = $tagWord.length; i--; ) {
             tags.push($($tagWord[i]).text().substring(0, $($tagWord[i]).text().length - 1).trim());
         }

         /*Then if you only want the unique tags entered:*/
         var uqTags = $.unique(tags);
         alert(uqTags.toSource());

     });

$.map($('.tag span'),function(e,i){return $(e).text().trim();})

<input type="text" name="to_addresses" class="to_addresses" data-role="tagsinput" >

$emails = []
$.map($(".tagsinput span span"),function(e,i){
$emails.push($(e).text().trim());
})

function getKeywords() {
  return $.map($('.tag span'),function(e,i){
    return $(e).text().trim();
  });
}