SOURCE

function sj(s,obj){
		$("#encode").val(s);
		$("#sels").text($(obj).text());
	}
    function base64_encode() {
		var encode = $("#encode").val();
		if(encode==1){
			var str = CryptoJS.enc.Utf8.parse(jQuery("#content").val());
			var base64 = CryptoJS.enc.Base64.stringify(str);
		}else{
			var str = jQuery("#content").val();
			var base64 = encode64gb2312(str);
		}
        jQuery("#result").val(base64);
    }
    function base64_decode() {
		var encode = $("#encode").val();
		if(encode==1){
			var words = CryptoJS.enc.Base64.parse(jQuery("#content").val());
			jQuery("#result").val(words.toString(CryptoJS.enc.Utf8));
		}else{
			var words = jQuery("#content").val();
			var base64 = decode64gb2312(words);
			jQuery("#result").val(base64);
		}
    }

	 function Empty() {
        document.getElementById('content').value = '';
        document.getElementById('result').value = '';
        document.getElementById('content').select();
    }
	
    function GetFocus() {
			document.getElementById('content').focus();
    }

<div class="panel panel-default">
<div class="panel-heading">
<div class="media">
<div class="media-body">
<h4 class="media-heading">Base64加密、解密</h4> 
</div>
</div>
</div>
<div class="panel-body">
<div>
<textarea id="content" name="RawJson" class="json_input" rows="10" style="width: 100%;" spellcheck="false" placeholder="请输入Base64编码字符串"></textarea>
</div>
<div class="btn-group" role="group" aria-label="...">
<button type="button" class="btn btn-primary" onclick="base64_encode();">BASE64加密</button>
<button type="button" class="btn btn-primary" onclick="base64_decode();">BASE64解密</button>
<button type="button" class="btn btn-danger" onclick="Empty();">清空结果</button>
</div>
<div class="btn-group" role="group" aria-label="...">
<button id="sels" type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
UTF-8<span class="caret"></span>
</button>
<ul class="dropdown-menu">
<li><a href="javascript:;" onclick="sj(1,this)">UTF-8</a></li>
<li><a href="javascript:;" onclick="sj(2,this)">GB2312</a></li>
</ul>
</div>
<div style="padding-top: 10px;">
<textarea id="result" name="RawJson" class="json_input" rows="10" style="width: 100%;" spellcheck="false" placeholder="加密或解密后的Base64编码字符串"></textarea>
</div>
</div>
<input type="hidden" id="encode" value="1" />
<div class="panel-footer"></div>
</div>