diff --git a/advagg_js_compress/jshrink.inc b/advagg_js_compress/jshrink.inc
index 5c0699fc..94d38337 100644
--- a/advagg_js_compress/jshrink.inc
+++ b/advagg_js_compress/jshrink.inc
@@ -80,6 +80,13 @@ class Minifier
      */
     protected $input;
 
+    /**
+     * Length of input javascript.
+     *
+     * @var int
+     */
+    protected $len = 0;
+
     /**
      * The location of the character (in the input string) that is next to be
      * processed.
@@ -115,11 +122,11 @@ class Minifier
      * @var array
      */
     protected $options;
-
+    
     /**
      * These characters are used to define strings.
      */
-    protected $stringDelimiters = array("'", '"', '`');
+    protected $stringDelimiters = ['\'' => true, '"' => true, '`' => true];
 
     /**
      * Contains the default options for minification. This array is merged with
@@ -128,7 +135,7 @@ class Minifier
      *
      * @var array
      */
-    protected static $defaultOptions = array('flaggedComments' => true);
+    protected static $defaultOptions = ['flaggedComments' => true];
 
     /**
      * Contains lock ids which are used to replace certain code patterns and
@@ -136,7 +143,7 @@ class Minifier
      *
      * @var array
      */
-    protected $locks = array();
+    protected $locks = [];
 
     /**
      * Takes a string containing javascript and removes unneeded characters in
@@ -146,7 +153,7 @@ class Minifier
      * @param  array       $options Various runtime options in an associative array
      * @throws \Exception
      * @return bool|string
-     */
+     */  
     public static function minify($js, $options = array())
     {
         try {
@@ -199,9 +206,7 @@ class Minifier
     protected function initialize($js, $options)
     {
         $this->options = array_merge(static::$defaultOptions, $options);
-        $js = str_replace("\r\n", "\n", $js);
-        $js = str_replace('/**/', '', $js);
-        $this->input = str_replace("\r", "\n", $js);
+        $this->input = str_replace(["\r\n", '/**/', "\r"], ["\n", "", "\n"], $js);   
 
         // We add a newline to the end of the script to make it easier to deal
         // with comments at the bottom of the script- this prevents the unclosed
@@ -214,6 +219,18 @@ class Minifier
         $this->b = $this->getReal();
     }
 
+  /**
+   * Characters that can't stand alone preserve the newline.
+   *
+   * @var array
+   */
+		protected $noNewLineCharacters = [
+		  '(' => true,
+		  '-' => true,
+		  '+' => true,
+		  '[' => true,
+		  '@' => true];
+    
     /**
      * The primary action occurs here. This function loops through the input string,
      * outputting anything that's relevant and discarding anything that is not.
@@ -225,7 +242,7 @@ class Minifier
                 // new lines
                 case "\n":
                     // if the next line is something that can't stand alone preserve the newline
-                    if ($this->b && strpos('(-+[@', $this->b) !== false) {
+                    if ($this->b !== false && isset($this->noNewLineCharacters[$this->b])) {
                         echo $this->a;
                         $this->saveString();
                         break;
@@ -319,7 +336,7 @@ class Minifier
 
             // Otherwise we start pulling from the input.
         } else {
-            $char = substr($this->input, $this->index, 1);
+            $char = $this->index < $this->len ? $this->input[$this->index] : false;
 
             // If the next character doesn't exist return false.
             if (isset($char) && $char === false) {
@@ -332,7 +349,7 @@ class Minifier
 
         // Normalize all whitespace except for the newline character into a
         // standard space.
-        if ($char !== "\n" && ord($char) < 32) {
+        if ($char !== "\n" && $char < "\x20") {
             return ' ';
         }
 
@@ -383,7 +400,7 @@ class Minifier
      */
     protected function processOneLineComments($startIndex)
     {
-        $thirdCommentString = substr($this->input, $this->index, 1);
+        $thirdCommentString = $this->index < $this->len ? $this->input[$this->index] : false;
 
         // kill rest of line
         $this->getNext("\n");
@@ -472,7 +489,7 @@ class Minifier
         $this->index = $pos;
 
         // Return the first character of that string.
-        return substr($this->input, $this->index, 1);
+        return  $this->index < $this->len ? $this->input[$this->index] : false;
     }
 
     /**
@@ -501,10 +518,9 @@ class Minifier
         echo $this->a;
 
         // Loop until the string is done
-        while (true) {
+        while (($this->a = $this->getChar()) !== false) {
 
             // Grab the very next character and load it into a
-            $this->a = $this->getChar();
 
             switch ($this->a) {
 
@@ -603,7 +619,7 @@ class Minifier
         /* lock things like <code>"asd" + ++x;</code> */
         $lock = '"LOCK---' . crc32(time()) . '"';
 
-        $matches = array();
+        $matches = [];
         preg_match('/([+-])(\s+)([+-])/S', $js, $matches);
         if (empty($matches)) {
             return $js;