Prototype - $R() Method

The $R() function is simply a short hand to writing new ObjectRange(lowerBound, upperBound, excludeBounds).

Syntax

$R(start, end[, exclusive = false]);

Here, start is the starting element of the range and end is the last element of the range. If exclusive flag is set to false, then it will include the ending elements, otherwise it will not be included in the range.

Return Value

Range Object.

Example

<html>
   <head>
      <title>Prototype examples</title>
      <script type = "text/javascript" src = "/javascript/prototype.js"></script>
      
      <script>
         function ShowValues() {
            var range = $R(10, 20, false);
            
            range.each(function(value, index) {
               alert(value);
            });
         }
      </script>
   </head>
   
   <body>
      <p>Click "Show Value" button to see the result</p>
      
      <form>
         <input type = "button" value = "Show Value" onclick = "ShowValues();"/>
      </form>
      
   </body>
</html>

Output

More Examples

Following statement returns true value −

$R(0, 10).include(10);

Following statement returns a string "0, 1, 2, 3, 4, 5" −

$A($R(0, 5)).join(', ');

Following statement returns a string "aa, ab, ac, ad, ae, af, ag, ah" −

$A($R('aa', 'ah')).join(', ');

Following statement returns false −

$R(0, 10, true).include(10);

Following statement will be invoked 10 times for value = 0 to 9 −

$R(0, 10, true).each(function(value) {
   // invoked 10 times for value = 0 to 9
});

prototype_utility_methods.htm