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Re: json.js breaks for-in loops

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  • Stephen M. McKamey
    ... toJSONString I ... make ... A little late to the conversation but... another alternative could be to use the typeof operator (assuming one was iterating
    Message 1 of 10 , Nov 13, 2006
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      --- In json@yahoogroups.com, Tom Metro <tmetro+json@...> wrote:
      >
      > Peter Michaux wrote:
      > > By extending the Object.prototype with the new property
      toJSONString I
      > > can no longer use for-in loops in my JavaScript.
      >
      > As another poster mentioned, using hasOwnProperty(), is the way to
      make
      > the intended behavior work. My understanding is that hasOwnProperty()
      > isn't widely supported yet.

      A little late to the conversation but... another alternative could be
      to use the typeof operator (assuming one was iterating over data):

      for(k in obj)
      if("function"!=typeof obj[k])
      foo(k);

      Thanks,
      smm
    • Martin Cooper
      ... Sure - if the for loop is in your own code, and not some other package that you re just trying to make use of. This issue really needs to be fixed in the
      Message 2 of 10 , Nov 13, 2006
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        On 11/13/06, Stephen M. McKamey <jsonml@...> wrote:
        >
        > --- In json@yahoogroups.com, Tom Metro <tmetro+json@...> wrote:
        > >
        > > Peter Michaux wrote:
        > > > By extending the Object.prototype with the new property
        > toJSONString I
        > > > can no longer use for-in loops in my JavaScript.
        > >
        > > As another poster mentioned, using hasOwnProperty(), is the way to
        > make
        > > the intended behavior work. My understanding is that hasOwnProperty()
        > > isn't widely supported yet.
        >
        > A little late to the conversation but... another alternative could be
        > to use the typeof operator (assuming one was iterating over data):
        >
        > for(k in obj)
        > if("function"!=typeof obj[k])
        > foo(k);


        Sure - if the for loop is in your own code, and not some other package that
        you're just trying to make use of.

        This issue really needs to be fixed in the JSON code, since there's no way
        you can rely on it being fixed in all the other code out there that you
        might want to use.

        --
        Martin Cooper


        Thanks,
        > smm
        >
        >
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
        >


        [Non-text portions of this message have been removed]
      • Stephen M. McKamey
        // This should do what you are asking for while staying // current with Crockford s latest code: // after json.js has loaded... // define a namespace to
        Message 3 of 10 , Nov 13, 2006
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          // This should do what you are asking for while staying
          // current with Crockford's latest code:

          // after json.js has loaded...
          // define a namespace to minimize footprint
          var JSON = {};

          // add all of the methods
          JSON.arrayToJSONString = Array.prototype.toJSONString;
          JSON.booleanToJSONString = Boolean.prototype.toJSONString;
          JSON.dateToJSONString = Date.prototype.toJSONString;
          JSON.numberToJSONString = Number.prototype.toJSONString;
          JSON.objectToJSONString = Object.prototype.toJSONString;
          JSON.stringToJSONString = String.prototype.toJSONString;
          JSON.parseJSON = String.prototype.parseJSON;

          // remove all the methods from intrinsic objects
          delete(Array.prototype.toJSONString);
          delete(Boolean.prototype.toJSONString);
          delete(Date.prototype.toJSONString);
          delete(Number.prototype.toJSONString);
          delete(Object.prototype.toJSONString);
          delete(String.prototype.toJSONString);
          delete(String.prototype.parseJSON);

          --- In json@yahoogroups.com, "Martin Cooper" <mfncooper@...> wrote:
          > Sure - if the for loop is in your own code, and not some other
          package that
          > you're just trying to make use of.
          >
          > This issue really needs to be fixed in the JSON code, since there's
          no way
          > you can rely on it being fixed in all the other code out there that
          you
          > might want to use.
        • Martin Cooper
          ... Right. But I don t understand the resistance (or, actually, just lack of any feedback at all) to having the kind of solution I described before (in another
          Message 4 of 10 , Nov 13, 2006
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            On 11/13/06, Stephen M. McKamey <jsonml@...> wrote:
            >
            > // This should do what you are asking for while staying
            > // current with Crockford's latest code:


            Right. But I don't understand the resistance (or, actually, just lack of any
            feedback at all) to having the kind of solution I described before (in
            another thread) incorporated into the original source code, so that we don't
            have to be going and deleting things like that. Here's what I suggested
            before, which is largely the same as yours, except that mine avoids creation
            where yours utilises deletion and is necessarily separate (and hence a
            little less easily maintained) from the original:

            http://tech.groups.yahoo.com/group/json/message/557

            --
            Martin Cooper


            // after json.js has loaded...
            > // define a namespace to minimize footprint
            > var JSON = {};
            >
            > // add all of the methods
            > JSON.arrayToJSONString = Array.prototype.toJSONString;
            > JSON.booleanToJSONString = Boolean.prototype.toJSONString;
            > JSON.dateToJSONString = Date.prototype.toJSONString;
            > JSON.numberToJSONString = Number.prototype.toJSONString;
            > JSON.objectToJSONString = Object.prototype.toJSONString;
            > JSON.stringToJSONString = String.prototype.toJSONString;
            > JSON.parseJSON = String.prototype.parseJSON;
            >
            > // remove all the methods from intrinsic objects
            > delete(Array.prototype.toJSONString);
            > delete(Boolean.prototype.toJSONString);
            > delete(Date.prototype.toJSONString);
            > delete(Number.prototype.toJSONString);
            > delete(Object.prototype.toJSONString);
            > delete(String.prototype.toJSONString);
            > delete(String.prototype.parseJSON);
            >
            > --- In json@yahoogroups.com, "Martin Cooper" <mfncooper@...> wrote:
            > > Sure - if the for loop is in your own code, and not some other
            > package that
            > > you're just trying to make use of.
            > >
            > > This issue really needs to be fixed in the JSON code, since there's
            > no way
            > > you can rely on it being fixed in all the other code out there that
            > you
            > > might want to use.
            >
            >
            >
            >
            >
            >
            > Yahoo! Groups Links
            >
            >
            >
            >
            >


            [Non-text portions of this message have been removed]
          • Douglas Crockford
            JavaScript is an imperfect language. The weird interaction between augmentation of prototypes with the for..in statement is evidence of this. This defect in
            Message 5 of 10 , Nov 14, 2006
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              JavaScript is an imperfect language. The weird interaction between
              augmentation of prototypes with the for..in statement is evidence of
              this. This defect in the language requires that for..in blocks
              explicitly filter out unwanted stuff that is dredged up from the
              prototype chain. See http://yuiblog.com/blog/2006/09/26/for-in-intrigue/

              json.js provides the same API that will be built into ECMAScript
              Fourth Edition. That means that if your program works with json.js,
              then it will work even better when the language is revised.

              Some people do not have the luxury of being forward looking. They have
              to work with bad code that does not filter for..in, or they claim the
              right to write bad code themselves. Those people should not be using
              json.js. Fortunately, JSON encoding and decoding is so easy, there
              isn't much effort required to make an implementation that works with
              bad code.

              JSON is a standard data representation. The json.js implementation is
              not the standard. It is a reference implementation. You are free to
              use it in any way that you want, or to not use it.
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