The greplin programming challenge (problem 1)-functional-style.js

(function(str){
  var maxPalin='';
  
  for(var i=0,len=str.length;i<len;++i){
    var letter=str[i],substr;
    
    for(var j=i;j<len;++j){
      if(letter == str[j]){
        maxPalin=(function(substr){
          return (function(substr){
            for(var i=0,len=substr.length;i<=len/2-1;++i){
              if(substr[i] != substr[len-i-1]){
                return false;
              }
            }
            return true;
          }(substr)) ? (maxPalin.length<substr.length ? substr : maxPalin) : maxPalin;
        }(substr=str.slice(i,j+1))); 
      }
    }
  }
  return maxPalin;
}("fourscoreandsevenyearsagoourfaathersbroughtforthonthiscontainentanewnationconceivedinzLibertyanddedicatedtothepropositionthatallmenarecreatedequalNowweareengagedinagreahtcivilwartestingwhetherthatnaptionoranynartionsoconceivedandsodedicatedcanlongendureWeareqmetonagreatbattlefiemldoftzhatwarWehavecometodedicpateaportionofthatfieldasafinalrestingplaceforthosewhoheregavetheirlivesthatthatnationmightliveItisaltogetherfangandproperthatweshoulddothisButinalargersensewecannotdedicatewecannotconsecratewecannothallowthisgroundThebravelmenlivinganddeadwhostruggledherehaveconsecrateditfaraboveourpoorponwertoaddordetractTgheworldadswfilllittlenotlenorlongrememberwhatwesayherebutitcanneverforgetwhattheydidhereItisforusthelivingrathertobededicatedheretotheulnfinishedworkwhichtheywhofoughtherehavethusfarsonoblyadvancedItisratherforustobeherededicatedtothegreattdafskremainingbeforeusthatfromthesehonoreddeadwetakeincreaseddevotiontothatcauseforwhichtheygavethelastpfullmeasureofdevotionthatweherehighlyresolvethatthesedeadshallnothavediedinvainthatthisnationunsderGodshallhaveanewbirthoffreedomandthatgovernmentofthepeoplebythepeopleforthepeopleshallnotperishfromtheearth"));

The greplin programming challenge (problem 1)-low-efficiency.js

(function(str){
  var maxPalin='';
  
  function isPalin(substr){
    for(var i=0,len=substr.length;i<=len/2-1;++i){
      if(substr[i] != substr[len-i-1]){
        return false;
      }
    }
    return true;
  }

  function group(seq,step){
    var len,g=[],i;

    if(seq && step>0 && step<=(len=seq.length)){
      for(i=0,len-=step;i<=len;++i){
        g.push(seq.slice(i,i+step));
      }
    }
    return g;
  }
  
  for(var i=str.length;i>0;i--){
    var g=group(str,i);

    for(var j=0;j<g.length;++j){
      if(isPalin(maxPalin=g[j])){
        return maxPalin;
      }
    }
  }
}("fourscoreandsevenyearsagoourfaathersbroughtforthonthiscontainentanewnationconceivedinzLibertyanddedicatedtothepropositionthatallmenarecreatedequalNowweareengagedinagreahtcivilwartestingwhetherthatnaptionoranynartionsoconceivedandsodedicatedcanlongendureWeareqmetonagreatbattlefiemldoftzhatwarWehavecometodedicpateaportionofthatfieldasafinalrestingplaceforthosewhoheregavetheirlivesthatthatnationmightliveItisaltogetherfangandproperthatweshoulddothisButinalargersensewecannotdedicatewecannotconsecratewecannothallowthisgroundThebravelmenlivinganddeadwhostruggledherehaveconsecrateditfaraboveourpoorponwertoaddordetractTgheworldadswfilllittlenotlenorlongrememberwhatwesayherebutitcanneverforgetwhattheydidhereItisforusthelivingrathertobededicatedheretotheulnfinishedworkwhichtheywhofoughtherehavethusfarsonoblyadvancedItisratherforustobeherededicatedtothegreattdafskremainingbeforeusthatfromthesehonoreddeadwetakeincreaseddevotiontothatcauseforwhichtheygavethelastpfullmeasureofdevotionthatweherehighlyresolvethatthesedeadshallnothavediedinvainthatthisnationunsderGodshallhaveanewbirthoffreedomandthatgovernmentofthepeoplebythepeopleforthepeopleshallnotperishfromtheearth"));

The greplin programming challenge (problem 1)-normal-style.js

(function(str){
  var maxPalin='';
  
  function isPalin(substr){
    for(var i=0,len=substr.length;i<=len/2-1;++i){
      if(substr[i] != substr[len-i-1]){
        return false;
      }
    }
    return true;
  }
  
  for(var i=0,len=str.length;i<len;++i){
    var letter=str[i],substr;
    
    for(var j=i;j<len;++j){
      if(letter==str[j] && isPalin(substr=str.slice(i,j+1))){
        maxPalin=substr.length > maxPalin.length ? substr : maxPalin;
      }
    }
  }
  return maxPalin;
}("fourscoreandsevenyearsagoourfaathersbroughtforthonthiscontainentanewnationconceivedinzLibertyanddedicatedtothepropositionthatallmenarecreatedequalNowweareengagedinagreahtcivilwartestingwhetherthatnaptionoranynartionsoconceivedandsodedicatedcanlongendureWeareqmetonagreatbattlefiemldoftzhatwarWehavecometodedicpateaportionofthatfieldasafinalrestingplaceforthosewhoheregavetheirlivesthatthatnationmightliveItisaltogetherfangandproperthatweshoulddothisButinalargersensewecannotdedicatewecannotconsecratewecannothallowthisgroundThebravelmenlivinganddeadwhostruggledherehaveconsecrateditfaraboveourpoorponwertoaddordetractTgheworldadswfilllittlenotlenorlongrememberwhatwesayherebutitcanneverforgetwhattheydidhereItisforusthelivingrathertobededicatedheretotheulnfinishedworkwhichtheywhofoughtherehavethusfarsonoblyadvancedItisratherforustobeherededicatedtothegreattdafskremainingbeforeusthatfromthesehonoreddeadwetakeincreaseddevotiontothatcauseforwhichtheygavethelastpfullmeasureofdevotionthatweherehighlyresolvethatthesedeadshallnothavediedinvainthatthisnationunsderGodshallhaveanewbirthoffreedomandthatgovernmentofthepeoplebythepeopleforthepeopleshallnotperishfromtheearth"));