If you write script that has a lot String content mixed with variables, I'm sure you're doing a lot of heavy concatenation.
Building string combos with quotes and apostrophes sprinkled all over a script gets confusing. The way I like to keep this confusion to a minimum is to write my static markup separately. This allows me to make sure it shows up as intended. Then I concatenate my variables in all the places that need to have dynamic content.

Taking static markup or script and wrapping quotes around every line is a chore so I made this Concatenation Tool to help with that.

Currently I've only made this support languages I'm using mostly. If I have to use a new language I'd just add it in.

Below are some basic use case examples of where a concatenation tool can be useful.

JavaScript
Concatenating a content to add to a Jquery UI Dialog.
In this example I purposely used he "text()" method to show the XML content instead of "html()".

    <script type="text/javascript">
                $(document).ready(function(){
                var ns = "";
                ns += "<LIBRARY>";
                ns += "    <BOOK>";
                ns += "        <TITLE id=\"2356\">Charlotte's Web</TITLE>";
                ns += "        <AUTHOR>E. B. White</AUTHOR>";
                ns += "        <FAMOUS_SAYING>\"Always be on the lookout for the presence of wonder.\"</FAMOUS_SAYING>";
                ns += "    </BOOK>";
                ns += "    <BOOK>";
                ns += "        <TITLE id=\"95\">Scuffy the Tugboat</TITLE>";
                ns += "        <AUTHOR>Gertrude Crampton</AUTHOR>";
                ns += "        <FAMOUS_SAYING>\"Toot, tooot!\" cried the frightened tugboat.</FAMOUS_SAYING>";
                ns += "    </BOOK>";
                ns += "</LIBRARY>";
                $("#myDialog").dialog({width:400, height:400});
                $("#myDialog p").text(ns);
                });
    </script>

Python
Concatenating with qoutes

ns = ""
ns += "<LIBRARY>"
ns += "    <BOOK>"
ns += "        <TITLE id=\"2356\">Charlotte's Web</TITLE>"
ns += "        <AUTHOR>E. B. White</AUTHOR>"
ns += "        <FAMOUS_SAYING>\"Always be on the lookout for the presence of wonder.\"</FAMOUS_SAYING>"
ns += "    </BOOK>"
ns += "    <BOOK>"
ns += "        <TITLE id=\"95\">Scuffy the Tugboat</TITLE>"
ns += "        <AUTHOR>Gertrude Crampton</AUTHOR>"
ns += "        <FAMOUS_SAYING>\"Toot, tooot!\" cried the frightened tugboat.</FAMOUS_SAYING>"
ns += "    </BOOK>"
ns += "</LIBRARY>"
print(ns)

Python concatenation with triple quotes to preserve the carriage returns

ns="""<LIBRARY>
    <BOOK>
        <TITLE id="2356">Charlotte's Web</TITLE>
        <AUTHOR>E. B. White</AUTHOR>
        <FAMOUS_SAYING>"Always be on the lookout for the presence of wonder."</FAMOUS_SAYING>
    </BOOK>
    <BOOK>
        <TITLE id="95">Scuffy the Tugboat</TITLE>
        <AUTHOR>Gertrude Crampton</AUTHOR>
        <FAMOUS_SAYING>"Toot, tooot!" cried the frightened tugboat.</FAMOUS_SAYING>
    </BOOK>
</LIBRARY>"""
print(ns)

Concatenation with regular quotes

Concatenation of blocks of text with triple quotes

JSFL
Concatenating a XUL markup string for building Flash IDE Panel with JSFL.

if(fl.documents.length == 0){
	fl.createDocument("timeline");
}
//------------------------------------------------------------
//An existing folder for the panel's source to be written to.
//------------------------------------------------------------
var appFolderName="jsflUI_sample";
var date=new Date();
function writePanelSource()
{
	var code = '';
	code += '<overlay>';
	code += '	<dialog id="app" title="Sample UI">';
	code += '		<hbox>';
	code += '			<spacer/>';
	code += '			<button id="b0" label="Button"/>';
	code += '		</hbox>';
	code += '		<separator/>';
	code += '		<vbox>';
	code += '			<label control="f0" value="Field 1" align="left"/>';
	code += '			<textbox id="f0" size="50" value="'+date.toString()+'"/>';
	code += '			<label control="f1" value="Field 2:" align="left"/>';
	code += '			<textbox id="f1" size="50" value=""/>';
	code += '		</vbox>';
	code += '		<checkbox id="cb0" label="Checkbox 1" checked="false" />';
	code += '		<checkbox id="cb1" label="Checkbox 2" checked="false" />';
	code += '	</dialog>';
	code += '</overlay>';
	FLfile.write(fl.configURI + "Commands/"+appFolderName+"/panelsource.xml", code);
	return code;
}

//----------------------------------------------------------------
//Writes the markup to "appFolderName" of Flash's "Commands folder
//----------------------------------------------------------------
writePanelSource();

//-------------------------------
//Open the Panel in Flash's IDE
//-------------------------------
fl.getDocumentDOM().xmlPanel(fl.configURI + "Commands/"+appFolderName+"/panelsource.xml");

Panel UI dialog from JSFL

SharePoint
Concatenating CAML querys.

function getListData()
{
	var clientContext = new SP.ClientContext.get_current();
	var web = clientContext.get_web();
	var userInfoList = web.get_lists().getByTitle('user_list')
	var camlQuery = new SP.CamlQuery();
	var caml = '';
	caml += '<View>';
	caml += '	<Query>';
	caml += '		<OrderBy>';
	caml += '			<FieldRef Name="Title" Ascending="False" />';
	caml += '		</OrderBy>';
	caml += '	</Query>';
	caml += '</View>';
	camlQuery.set_viewXml(caml);
	collListItem = userInfoList.getItems(camlQuery);
	clientContext.load(collListItem);
	var onQuerySucceeded=function(sender, args)
	{
		var oitem;
		var s='';
		var n=0;
		var len=collListItem.get_count();
		var results=[];
		while(n < len)
		{
			oitem = collListItem.itemAt(n);
			s+="Title:"+oitem.get_item("Title")+"<br></br>";
			n++;
		}
		$("#output").append(s);
	}
	var onQueryFailed=function(sender, args)
	{
		alert("Failed getting data.")
	}
	clientContext.executeQueryAsync
        (
        Function.createDelegate(this, onQuerySucceeded),
        Function.createDelegate(this, onQueryFailed)
        );
}

Output of Title column from a SharePoint 2010 list.

Here I extended the TitleWindow to make it be automatically added with the PopUpManager.
Also all the child components get carried over after PopUpManager is used.
I did this so I could lazily use MXML and all references to this component instance stay intact, because the PopUpManager is using the same instance of the MXML component.

The "Move Left" and "Move Right" buttons show that the references are ok.

MXML in "net/keithhair/FloatWindow.mxml"

 
<?xml version="1.0" encoding="utf-8"?>
<s:TitleWindow creationComplete="init()"
			   xmlns:fx="http://ns.adobe.com/mxml/2009"
			   xmlns:s="library://ns.adobe.com/flex/spark"
			   xmlns:mx="library://ns.adobe.com/flex/mx"
			   autoLayout="true"
			   width="400"
			   height="300">
	<fx:Script>
		<![CDATA[
			import mx.events.CloseEvent;
			import mx.managers.PopUpManager;
			import spark.components.Group;
			import spark.components.VGroup;
 
			protected var _vgroup:Group;
 
			protected function init():void
			{
				var p:String;
				var n:int;
				var a:Array=[];
				var _parent:DisplayObject=parent;
				//---------------------------------------------
				//Remove all the child elements store
				//the references in an Array
				//---------------------------------------------
				n=numElements - 1;
				while (n > -1)
				{
					a.push(removeElementAt(n));
					n--;
				}
				Group(parent).removeElement(this);
				//---------------------------------------------
				//Add a popup of a this TitleWindow instance,
				//Create a layout container and add all
				//the children back into it.
				//---------------------------------------------
				PopUpManager.addPopUp(this, _parent);
				n=a.length - 1;
				_vgroup=new VGroup();
				_vgroup.setStyle("top",5);
				_vgroup.setStyle("bottom",5);
				_vgroup.setStyle("left",5);
				_vgroup.setStyle("right",5);
				addElement(_vgroup);
				while (n > -1)
				{
					_vgroup.addElement(a[n]);
					n--;
				}
				addEventListener(CloseEvent.CLOSE, closer);
				PopUpManager.centerPopUp(this);
				p=null;
				n=0;
				a=null;
			}
 
			protected function closer(evt:CloseEvent):void
			{
                                removeEventListener(CloseEvent.CLOSE, arguments.callee);
				PopUpManager.removePopUp(this);
			}
		]]>
	</fx:Script>
</s:TitleWindow>
 

Now I can simply use MXML to make my draggable windows.
The window is draggable and all the
MXML children are there too.

 
	<keithhair:FloatWindow id="mywindow"
			       title="My Window"
			       width="250"
			       height="300">
		<mx:TabNavigator width="100%"
				 height="100%">
			<mx:VBox label="Buttons">
				<s:Button/>
				<s:Button/>
				<s:Button/>
			</mx:VBox>
			<mx:VBox label="Checkboxes">
				<s:CheckBox/>
				<s:CheckBox/>
				<s:CheckBox/>
			</mx:VBox>
			<mx:VBox label="TextAreas">
				<s:TextArea/>
				<s:TextArea/>
			</mx:VBox>
		</mx:TabNavigator>
	</keithhair:FloatWindow>
 

If you know of a more efficient way that does this or can make this better just add your comments to my blog.

 
/*-----------------------------------
	Recursively replace nodeNames.
-------------------------------------*/
      private function findAndReplaceTagNames
      (xml:XML,find:String,replace:String):XML
      {
          if(xml.localName() == find){
              xml.setLocalName(replace);
          }
          var n:int=0;
          var c:XML;
          while(n <xml.children().length()){
              c=xml.children()[n];
              findAndReplaceTagNames(c,find,replace);
              n++;
          }
          return xml;
      }
 
/*-----------------------------------------
	Recursively replace attributes.
-------------------------------------------*/
      private function findAndReplaceAttributeNames
      (xml:XML,find:String,replace:String,in_tags_named:String=""):XML
      {
          var ok:Boolean=true;
          if(in_tags_named != "" && xml.localName() != in_tags_named){
              ok=false;
          }
          if(xml.@[find] != null && ok){
              xml.@[replace]=xml.@[find];
              delete xml.@[find];
          }
          var n:int=0;
          var c:XML;
          while(n <xml.children().length()){
              c=xml.children()[n];
              findAndReplaceAttributeNames(c,find,replace);
              n++;
          }
          return xml;
      }
 
/*---------------------------------------------
	Recursively find and remove attributes.
-----------------------------------------------*/
      private function findAndRemoveAttributeNames
      (xml:XML,find:String,in_tags_named:String=""):XML
      {
          var ok:Boolean=true;
          if(in_tags_named != "" && xml.localName() != in_tags_named){
              ok=false;
          }
          if(xml.@[find] != null && ok){
              delete xml.@[find];
          }
          var n:int=0;
          var c:XML;
          while(n <xml.children().length()){
              c=xml.children()[n];
              findAndRemoveAttributeNames(c,find);
              n++;
          }
          return xml;
      }