OnClick Javascript Button causing error on field with separate lines.

Question

In the button code, the line

dog.colMrk__c = "{!Birth_Record__c.Characteristics__c}";

causes an error "Unexpected token ILLEGAL" when there are separate lines in the Characteristics field. Is there a way around this? Both fields are Long Text Area.

{!REQUIRESCRIPT("/soap/ajax/25.0/connection.js")} 
{!REQUIRESCRIPT("/soap/ajax/25.0/apex.js")} 

var pupIn = "{!Birth_Record__c.dog_Name2__c}"; 

if (pupIn != "") { 
alert("A dog record has already been created for this birth record. Please click the link next to Puppy Name to view that record.") 
}else{ 
var dog = new sforce.SObject("Dog__c"); 

dog.Name = "{!Birth_Record__c.Name}"; 
dog.sex__c = "{!Birth_Record__c.Gender__c}"; 
dog.Dame__c = "{!Birth_Record__c.Dame_ID__c}"; 
dog.Sire__c = "{!Birth_Record__c.Sire_ID__c}"; 

dog.colMrk__c = "{!Birth_Record__c.Characteristics__c}";

dog.Breed__c = "{!Birth_Record__c.Breed__c}"; 

var by = "{!YEAR( DATEVALUE(Birth_Record__c.Birth__c) )}"; 
var bm = "{!MONTH( DATEVALUE(Birth_Record__c.Birth__c) )}"; 
if (bm.length == 1){ 
bm = "0"+bm; 
} 
var bd = "{!DAY( DATEVALUE(Birth_Record__c.Birth__c) )}"; 
if (bd.length == 1){ 
bd = "0"+bd; 
} 
var b = by+"-"+bm+"-"+bd; 
dog.birthdate__c = b; 

var result = sforce.connection.create([dog]); 

if(result[0].getBoolean("success")){ 
var nextPg = result[0].id; 
var newRecords = []; 
var c = new sforce.SObject("Birth_Record__c"); 
c.id ="{!Birth_Record__c.Id}"; 
c.dog_Name2__c = result[0].id; 
newRecords.push(c); 
result = sforce.connection.update(newRecords); 
window.location = "/" + nextPg; 
}else{ 
alert('Could not create record '+result); 
} 
}

Answer 1

That's because you cannot have multiline strings in Javascript unless they are properly escaped.

Try JSENCODE on the string: dog.colMrk__c = "{! JSENCODE(Birth_Record__c.Characteristics__c) }";

JSENCODE documentation can be found here.