String object question

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  • Christopher Benson-Manica
    #1

    String object question


    <html>
    <head>
    <script>
    var s=String( 'foo' );
    alert( s );
    s.bar='bar';
    alert( s.bar );
    </script></head></html>

    Why does the second alert produce 'undefined'? Are string objects
    somehow special?

    --
    Christopher Benson-Manica | I *should* know what I'm talking about - if I
    ataru(at)cybers pace.org | don't, I need to know. Flames welcome.
    Tags: None
    • PDannyD
      #2
      Re: String object question

      Christopher Benson-Manica wrote:
      [color=blue]
      >
      > <html>
      > <head>
      > <script>
      > var s=String( 'foo' );
      > alert( s );
      > s.bar='bar';
      > alert( s.bar );
      > </script></head></html>
      >
      > Why does the second alert produce 'undefined'? Are string objects
      > somehow special?[/color]

      Shouldn't it be something like this?

      <html>
      <head>
      <script>
      var s=new String();
      s.first = "First string";
      alert(s.first);
      s.second = "Second string";
      alert(s.second) ;
      </script>
      </head>
      </html>

        Comment

        • Christopher Benson-Manica
          #3
          Re: String object question

          PDannyD <dan1970@scenic place.freeserve .co.uk> spoke thus:
          [color=blue]
          > Shouldn't it be something like this?[/color]
          [color=blue]
          > var s=new String();[/color]

          Yes, you're right. My way was trying to assign properties to a
          primitive string and of course you can't do that. Thank you.

          --
          Christopher Benson-Manica | I *should* know what I'm talking about - if I
          ataru(at)cybers pace.org | don't, I need to know. Flames welcome.

            Comment

            • Lee
              #4
              Re: String object question

              Christopher Benson-Manica said:[color=blue]
              >
              >
              ><html>
              > <head>
              > <script>
              > var s=String( 'foo' );
              > alert( s );
              > s.bar='bar';
              > alert( s.bar );
              ></script></head></html>
              >
              >Why does the second alert produce 'undefined'? Are string objects
              >somehow special?[/color]

              You didn't create a String object, just a simple string.
              Try it with:

              var s = new String( 'foo' );

                Comment

                • Christopher Benson-Manica
                  #5
                  Re: String object question

                  Lee <REM0VElbspamtr ap@cox.net> spoke thus:
                  [color=blue]
                  > You didn't create a String object, just a simple string.
                  > Try it with:[/color]
                  [color=blue]
                  > var s = new String( 'foo' );[/color]

                  Yes, that works. Here's a followup question though: Does the split()
                  method produce an array of string objects or primitive strings?

                  --
                  Christopher Benson-Manica | I *should* know what I'm talking about - if I
                  ataru(at)cybers pace.org | don't, I need to know. Flames welcome.

                    Comment

                    • Lee
                      #6
                      Re: String object question

                      Christopher Benson-Manica said:[color=blue]
                      >
                      >Lee <REM0VElbspamtr ap@cox.net> spoke thus:
                      >[color=green]
                      >> You didn't create a String object, just a simple string.
                      >> Try it with:[/color]
                      >[color=green]
                      >> var s = new String( 'foo' );[/color]
                      >
                      >Yes, that works. Here's a followup question though: Does the split()
                      >method produce an array of string objects or primitive strings?[/color]

                      They are primitive strings.
                      The following alerts "string", rather than "object":

                      <html>
                      <body>
                      <script type="text/javascript">
                      var token="alpha,be ta,gamma".split (",");
                      alert(typeof token[0]);
                      </script>
                      </body>
                      </html>

                        Comment

                        • RobB
                          #7
                          Re: String object question

                          Christopher Benson-Manica wrote:[color=blue]
                          > Lee <REM0VElbspamtr ap@cox.net> spoke thus:
                          >[color=green]
                          > > You didn't create a String object, just a simple string.
                          > > Try it with:[/color]
                          >[color=green]
                          > > var s = new String( 'foo' );[/color]
                          >
                          > Yes, that works. Here's a followup question though: Does the split()
                          > method produce an array of string objects or primitive strings?
                          >
                          > --
                          > Christopher Benson-Manica | I *should* know what I'm talking about -[/color]
                          if I[color=blue]
                          > ataru(at)cybers pace.org | don't, I need to know. Flames welcome.[/color]

                          This may help:

                          404 Not Found
                          http://www.chinalinuxpub.com/doc/oreillybookself/web/jscript/ch03_11.htm


                            Comment

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