Tim’s
Bandwagon

ActionScript trim function

ActionScript 2.0 doesn’t have a trim function to strip whitespace from the start and end of a string. Here’s a simple function I wrote because I couldn’t find a satisfactory example on Google!

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function trim(str:String):String
{
    var stripCharCodes = {
        code_9  : true, // tab
        code_10 : true, // linefeed
        code_13 : true, // return
        code_32 : true  // space
    };
    while(stripCharCodes["code_" + str.charCodeAt(0)] == true) {
        str = str.substring(1, str.length);
    }
    while(stripCharCodes["code_" + str.charCodeAt(str.length - 1)] == true) {
        str = str.substring(0, str.length - 1);
    }
    return str;
}

The horrible "code_" prefix hack is there because I don’t think there’s a native way to search an array or object for a key or value in ActionScript.

Update: just found this function at: frogstyle.ch. This one does a similar thing, but strips more characters.

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function trim(str:String):String
{
    for(var i = 0; str.charCodeAt(i) < 33; i++);
    for(var j = str.length-1; str.charCodeAt(j) < 33; j--);
    return str.substring(i, j+1);
}

Update: as3corelib has a static trim method in com.adobe.utils.StringUtil.

Published at 4:26 pm on July 23rd, 2007.
Topics: Flash

26 Comments

  1. This function has been a great help. Thanks!!!

    Comment by yiannis karadimas at 7:19 pm on February 10th, 2008 #link

  2. Thanks for valuable fucntion …it saves lot of time to write again !

    Comment by Baljeet at 6:20 pm on February 12th, 2008 #link

  3. Thanks man!

    Comment by yet another AS2 looney at 1:25 pm on March 11th, 2008 #link

  4. It worked for me. Great Code. Thanks for sharing.

    Comment by Suresh at 8:39 pm on August 9th, 2008 #link

  5. Thanks! This is short and clean: The way it should be.

    Comment by Greg Ferrell at 8:41 pm on August 21st, 2008 #link

  6. Thanks a lot! It really helps and works from the forst eseye! Спасибо

    Comment by quezak at 1:52 pm on August 28th, 2008 #link

  7. Thks for this good code snippet!

    Comment by pok at 6:09 pm on September 4th, 2008 #link

  8. Thanks , nice trim methods.

    Comment by Brent at 2:39 pm on October 7th, 2008 #link

  9. Hi Tim, great post…

    I just want to enhance your code since using loop counter outside loop block is unusual practice, i know, it’s working on flex but we don’t know if someday adobe fix those problem.

    protected function trim(str : String) : String
{
  var i : int = 0;
  var j : int = 0;

  for (i = 0; str.charCodeAt(i) < 33; i++);
  for (j = str.length - 1; str.charCodeAt(j) < 33; j--);

  return str.substring(i, j+1);
}

    Comment by Denny at 7:46 am on December 16th, 2008 #link

  10. Thanks for Greate help

    Comment by Jitendra Panwar at 8:31 am on December 17th, 2008 #link

  11. There is a static method in mx.utils.StringUtil class: StringUtil.trim()

    Comment by Rubi at 1:30 pm on January 7th, 2009 #link

  12. Re #11. Rubi.

    I’ve done a little searching and the mx.utils.StringUtil class doesn’t exist in the classes distributed with my version of Flash (CS3). I believe it is part of the Flex library.

    A quick google also revealed a class in as3corelib (com.adobe.utils.StringUtil) which also has a static trim method.

    Using either of these is probably better than using my function!

    Comment by Tim at 4:29 pm on January 7th, 2009 #link

  13. A few quick mods:

    1. I find it much more convenient in ECMAScript to have trim overloaded on the String prototype, as it’s unwaveringly applied to strings.
    2. running a substr on each loop is relatively slow. It’s harder, but faster, to just keep track of position.
    3. I’ve added a way to create the charcodes as needed, so you can, say, strip the ‘/’s off a pathname if you need to.
    String.prototype.trim = function (strip):String {
        if (!!strip)
            strip = " \t\r\n";
        var 
            codes = {},
            i,
            start=0,
            len=this.length;
        for (i=0; i<strip.length; i++)
            codes[strip.charCodeAt(i)]=1;
    while(codes[this.charCodeAt(start)]==1) 
        start++;
    len-=start;
    while(codes[this.charCodeAt(start+len-1)]==1)
        len--;
    return this.substr(start, len);
}

    Comment by Bryan Elliott at 4:08 pm on January 30th, 2009 #link

  14. Huh. Sorry about the formatting…

    Comment by Bryan Elliott at 4:08 pm on January 30th, 2009 #link

  15. Re #13, #14.

    Hi Bryan, thanks for posting. I took the liberty of re-formatting your post that the weblog software mangled. Hopefully it looks like you intended?

    Comment by Tim Brayshaw at 4:34 pm on January 30th, 2009 #link

  16. Thank you very much for this code! saved me time!

    Comment by AMeen at 6:23 am on February 4th, 2009 #link

  17. Here’s a lightweight regular expression to do it: myString = myString.replace(/^s+|s+$/g, ”);

    Comment by Anthony Sapien at 10:43 pm on March 9th, 2009 #link

  18. Re #17

    Hi Anthony, that looks like a good option. It’s worth remembering, though, that support for regular expressions only appears in ActionScript 3.0.

    Comment by Tim at 9:47 am on April 10th, 2009 #link

  19. Thanks for this, yours worked, the second didn’t.

    Comment by Eduardo Vaz de Mello at 8:20 pm on April 18th, 2009 #link

  20. Thanks!! You saved my time.

    Comment by Satish at 11:33 am on May 13th, 2009 #link

  21. corrected as and works well as … myString.replace(/^\s+|\s+$/g, ”);

    Comment by anonymous at 2:31 pm on October 7th, 2009 #link

  22. This is by far the easiest trim method:

    function trim(str:String) { return str.replace(/^s/, “”).replace(/s$/, “”); }

    Comment by Aaron at 9:40 pm on January 21st, 2010 #link

  23. mx.utils.StringUtil.trim(s:String):String com.adobe.utils.StringUtil.ltrim/rtrim/trim(s:String):String

    Comment by Kofa at 11:36 am on August 13th, 2010 #link 

  24. for(var i : int = 0; str.charCodeAt(i) < 33; i++);
if(i == str.length){
    return "";
}

    as i see, without this “if” statement our trim returns full string, if the string is consists with whitespaces only

    Comment by radistao at 10:35 am on November 25th, 2010 #link

  25. I just make a change at the last line, because it wasn’t work fine for me.

    public function trim(str:String):String {
    var i:int;
    var j:int;
    var length:int = str.length;

    for(i = 0; str.charCodeAt(i) < 33; i++) {}
    for(j = length-1; str.charCodeAt(j) < 33; j--) {}
    return str.substr(i, length-j);
}

    Comment by Bruno Lemos at 6:42 pm on March 15th, 2011 #link

  26. thanks a lot Tim. It really helped me about my trouble; I was checking two same strings( one is input the other is from xml) if they are same for as2 too but it seems that they weren’t same. In trace output I saw that one of strings has a hidden “n” in it. So I searched for the trim function and found your blog. thanks a lot again. it really helped me :)

    Comment by Alper BURMABIYIK at 5:16 pm on May 29th, 2011 #link

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