Regular Expressions in ActionScript

Regular expressions in ActionScript are handled using the RegExp class. Here are some examples of common regexp-related tasks in ActionScript.

package {
    import flash.display.Sprite;
    import flash.text.TextField;

    public class RegularExpressions extends Sprite {
        public function RegularExpressions() {
            var output:TextField = new TextField();
            output.width = 400;
            output.height = 400;
            addChild(output);

            // This tests whether a pattern matches a string.
            var match:Boolean = /p([a-z]+)ch/.test("peach");
            output.appendText(match.toString() + "\n");

            // In ActionScript, we don't need to compile the regex separately.
            // We can use it directly.
            var r:RegExp = /p([a-z]+)ch/;

            // Here's a match test like we saw earlier.
            output.appendText(r.test("peach").toString() + "\n");

            // This finds the match for the regexp.
            var result:Object = r.exec("peach punch");
            output.appendText(result[0] + "\n");

            // The index of the match can be found in the index property.
            output.appendText("idx: [" + result.index + " " + (result.index + result[0].length) + "]\n");

            // The exec method returns an array with the full match and any capturing groups.
            output.appendText(result.toString() + "\n");

            // To find all matches, we can use a loop with the exec method.
            var allMatches:Array = [];
            var str:String = "peach punch pinch";
            while ((result = r.exec(str)) !== null) {
                allMatches.push(result[0]);
            }
            output.appendText(allMatches.toString() + "\n");

            // To replace subsets of strings with other values:
            output.appendText(("a peach").replace(r, "<fruit>") + "\n");

            // To transform matched text with a function:
            function toUpper(match:String, ...args):String {
                return match.toUpperCase();
            }
            output.appendText(("a peach").replace(r, toUpper) + "\n");
        }
    }
}

This ActionScript code demonstrates various operations with regular expressions:

Testing if a pattern matches a string using the test method.
Finding matches using the exec method.
Getting information about matches, including their indices.
Finding all matches in a string.
Replacing matched substrings with new values.
Using a function to transform matched text.

Note that ActionScript’s regular expression handling is somewhat different from some other languages:

There’s no need to compile the regular expression separately; you can use regex literals directly.
The exec method is used for finding matches, and it returns null when no more matches are found.
To find all matches, you need to use a loop with exec.
There’s no direct equivalent to some of the more advanced methods available in other languages, but most common operations can be achieved through creative use of exec and replace.

For more information on regular expressions in ActionScript, refer to the ActionScript documentation on the RegExp class.

Text Templates in ActionScript

Json in ActionScript

Learn X By Example

Title here

Regular Expressions in ActionScript