Javascript code working with Firefox but not with IE... please help!

Discussion in 'Javascript' started by John Ca, Oct 4, 2009.

  1. John Ca

    John Ca Guest

    Hi all!

    I'm a javascript newbie, and I wrote a function who's purpose is to
    scan all paragraphs in a page, and then highlight certain keywords
    which I provide in advance and turn them into hyperlinks! Simple

    The problem is that the function works perfectly with Firefox (I am
    using latest version 3.5.3), but with Internet Explorer it does not
    work. I have tested it both with IE6 & IE7, and they both give me a
    javascript error and the script doesn't do anything.

    Since I am a total newbie when it comes to javascript I have
    absolutely no idea what the problem could be, especially since the
    script works as intended in Firefox! I would appreciate any help
    anyone could provide...

    I am calling the script function with an 'onload' event in the <body>

    Here is my script:

    function create_links() {

    var KeywordsArray = new Array
    var DocTextArray = document.getElementsByTagName("p")

    for (y in DocTextArray) {

    var DocText = document.getElementsByTagName("p")[y]
    var DocTextContent = DocText.innerHTML
    var DocTextNewContent

    for (x in KeywordsArray)
    var NewRegExp = new RegExp(KeywordsArray[x], "g");
    DocTextContent = DocTextContent.replace(NewRegExp,"<a
    href=\"\">" + KeywordsArray[x] + "</a>")

    DocText.innerHTML = DocTextContent

    Thanks in advance to anyone willing to help out!!!

    John Ca, Oct 4, 2009
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  2. The error message, which you have not posted, says what the problem is.
    (Granted, IE error messages can be cryptic and misleading by comparison,
    nevertheless you need to post them.) Please read the FAQ, especially
    So what? Firefox is Gecko-based, IE is MSHTML-based. Gecko supports
    Netscape/ JavaScript, IE/MSHTML supports Microsoft JScript.
    But you have not posted how you call it, which is rather important to know.
    This is not a quiz show.
    Thanks in advance for posting properly, including punctuation.

    Thomas 'PointedEars' Lahn, Oct 5, 2009
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  3. John Ca

    John Ca Guest

    Ok sorry, here is the requested information!

    The error message I get is:

    Line: 17
    Char: 3
    Error: 'undefined' is null or not an object
    Code: 0

    How I call the function is like this:

    <body onload="create_links();">

    Hope this clears things up!
    John Ca, Oct 5, 2009
  4. John Ca

    RobG Guest

    I guess this is an exercise you have set yourself as a way of

    As Thomas said, post the error message.
    It is more efficient to use an array literal:

    var KeywordsArray = ["Keyword1", "Keyword2", "Keyword3",

    As a convention, variable names starting with capital letters are
    reserved for constructors.

    getElementsByTagName returns an HTML collection[1], which is *like* an
    array in that its members can be accessed by index, but (in most
    browsers) it lacks all the other special features of an array. So I
    wouldn't call it an array, perhaps:

    var pCollection = ...;

    It is not a good idea to use to iterate over the members of an
    array (even though what you have is just array-like) as it may well
    return other properties of that object. I suspect that is your problem
    with IE - it is enumerating properties that you don't expect.

    You have a collection where the members can be accessed by index, so:

    for (var i=0, len=pCollection.length; i<len; i++) {
    You already have a reference to that collection, so don't get it again
    on every iteration. Also, what it returns is a reference to a p
    element, so name your variable to reflect that:

    var p = pCollection;

    It is considered a good idea to declare all variables at the start of
    a function (except for those used in loops). Some prefer to declare
    them where they are first used.
    Using innerHTML is not always a good idea, though it should be OK here
    provided your keywords don't match markup rather than content.
    Using to iterate over the members of an array again, see
    above. Use a normal for loop.

    You probably only want to match whole words, so add that condition to
    your regular expression:

    var NewRegExp = new RegExp('\\b' + KeywordsArray[x] + '\\b','g');

    You can reduce the number of steps if you assign directly to the
    innerHTML of the paragraph, e.g.

    DocText.innerHTML = DocText.innerHTML.replace(...);

    What you are trying to do has many foibles, it will only work well on
    content that fits your criteria exactly. Search the archives, this
    task has been attempted many times before. Here's a version of your
    script that works in IE:

    function create_links() {

    var keywords = ['Keyword1','Keyword2','Keyword3','Keyword4'],
    pCollection = document.getElementsByTagName("p"),

    for (var i=0, iLen=pCollection.length; i<iLen; i++) {
    p = pCollection;

    for (var j=0, jLen=keywords.length; j<jLen; j++) {
    word = keywords[j];
    re = new RegExp('\\b' + word + '\\b','g');
    p.innerHTML = p.innerHTML.replace(re,
    '<a href="">' + word + '</a>');

    1. <URL: >
    RobG, Oct 5, 2009
  5. John Ca

    John Ca Guest

    Rob, thank you SO MUCH for taking all that time to help me and explain
    everything step by step!!! The script you provided worked perfectly
    with both IE & Firefox, and also your insights were very helpful to my
    general understanding of Javascript!

    Again thanks!!! I really appreciate it!!!

    John Ca, Oct 5, 2009
  6. Well, in itself it doesn't really clear things up, as you do not say where
    line 17 is (and your unwise original line length makes it even harder to
    guess). First think, then post. And read the FAQ.

    However, now that RobG has pointed out the for-in iteration over a NodeList,
    the error message indicates that something goes wrong with that. Indeed, my
    test in IE 6 --

    javascript:var ps = document.getElementsByTagName("p"); var a = []; for
    (var p in ps) a.push(p); window.alert(a);

    [in the address bar, at]

    -- shows that in the MSHTML DOM the returned NodeList instance has an
    *enumerable* `length' property. Therefore,

    var DocTextArray = document.getElementsByTagName("p")

    for (y in DocTextArray) {


    var DocText = document.getElementsByTagName("p")["length"];

    at some point, after which the code would be equivalent to

    var DocTextContent = (42).innerHTML
    var DocTextNewContent

    for (x in KeywordsArray)
    var NewRegExp = new RegExp(KeywordsArray[x], "g");

    (I use `42' as a dummy number here as you have not posted or linked to the
    underlying markup, which you should have.)

    Then the following line (which is probably line 17 or nearby) resolves to

    DocTextContent = (undefined).replace(NewRegExp,"<a
    href=\"\">" + KeywordsArray[x] + "</a>")

    And `undefined' *is* (null or) not an object, so it does not have a
    replace() method to be called, which causes the aforementioned error

    Bottom line and solution: Do not use for-in iteration with host objects, use
    classic for-loops. And use a debugger and make some cut-down tests before

    Thomas 'PointedEars' Lahn, Oct 5, 2009
  7. John Ca

    John Ca Guest

    Hey Thomas,

    I think you have a major attitude problem man... but other than that
    thanks for at least being *willing* to help, just leave all the
    sarcasm to yourself next time! Cheers!

    John Ca, Oct 5, 2009
  8. If you think that my telling you exactly and in detaul where and how you
    made mistakes included any kind of sarcasm, you are the one having a serious
    attitude (and reading) problem for sure.

    This is not a free help desk. Rest assured that I am not going to spend my
    free time and help you next time. FOAD.

    Thomas 'PointedEars' Lahn, Oct 5, 2009
  9. John Ca

    John Ca Guest

    It's free last time I checked... also I find it sad that you feel the
    need to project your real life frustrations on an internet help board.
    So much pent up aggression was obvious from your first message... and
    your last message just proves my point.

    No I will not "**** off and die", but you definitely need to get some
    help/renew the meds prescription. Asshole.

    Get out more... and have a nice life!
    John Ca, Oct 5, 2009
  10. John Ca meinte:
    I read Thomas' psoting twice. What sarcasm are you talking about? (By
    Thomas' standards that was in fact a pretty tame response.) Instead you
    got a detailled explanation, why you can't iterate over the nodelist
    with for .. in. What's your problem with that?

    Gregor Kofler, Oct 5, 2009
  11. John Ca

    DonO Guest

    I think perhaps he's referencing such snarky remarks as...

    "Thanks in advance for posting properly, including punctuation."

    Making fun of his TIA for the help.

    In a later post however, he says, "If you think that my telling you
    exactly and in *detaul* where and how you
    made mistakes" so it's good to see we're all prone to errors I

    FWIW I'd rather people help or not help. I deal with enough
    personalities in my regular job.

    DonO, Oct 5, 2009
  12. DonO meinte:
    TIA for not quoting my signature the next time.

    CNR, Gregor
    Gregor Kofler, Oct 5, 2009
  13. John Ca

    GTalbot Guest

    "Instruction manual" directives just to post can certainly frustrate
    people. The tone with which PointedEars reply can make anyone feel
    inferior, especially the way he replies. Over-excessively nitpicking
    too. It seems it never occurred to people like PointedEars that he is
    obnoxious, authoritative, absolutely abrasive. PointedEars has weak
    social skills.

    "First think, then post. And read the FAQ. ": is that the kind of
    useful help one should (or would) expect when posting in c.l.j.?

    That famous c.l.j. FAQ is pretty long (89 Kilo-bytes; over 2000
    lines); it is sometimes vague and it is referring to furthermore
    reading ... to just post something in c.l.j.

    Posting Questions and Replies to comp.lang.javascript
    is 61 Kilo-bytes of more reading ... just to post at c.l.j.!

    Realistically speaking, a perfectly willing, obedient, compliant
    reader would have to read 150Kb before posting anything. And the first
    thing to do for him/her before posting would be to "Read recent
    relevant posts in c.l.js." How many? How recent? a week? a month?? How
    does one establish/distinguish what is and what is not a relevant post
    before making his first post in c.l.j.?

    The tone matters. The precise choice of words matters too. PointedEars
    will always be perceived by a large majority of people to have an
    attitude problem.

    "This is not a quiz show.",
    "Thanks in advance for posting properly, including punctuation. "
    "Please read the FAQ, especially
    <>, and act accordingly. "
    etc.: very typical PointedEars domesticating responses. Absolutely
    unneeded, unnecessarly abrasive.

    "FOAD": if that's not verbal abuse - and totally unneeded - , then
    what is it?

    GTalbot, Oct 6, 2009
  14. GTalbot meinte:
    That's not in the posting I was refering to.

    Gregor Kofler, Oct 6, 2009
  15. GTalbot kirjoitti:
    But certainly only people that really do not want the help that they need?
    Which tone? There is no tone in USENET or email messages. Your "tone" is
    in the eye of the beholder. Rule of thumb: always read messages without
    You are missing the point and everything with it. See what's happening?

    1) You are off topic.
    2) You are taking me with you.

    And I'd willing to bet $10 that you are in no position to judge his
    I guess that is, if not what one would expect, what one needs. And that
    exactly. I for one should print that and stick it between me and the
    send button :)
    It's not like that. One should read the FAQ "before posting" section and
    search the FAQ for his/hers issue. If not a FAQ, then search cljs.
    Posting comes after that. Preferably asking smart questions. That is,
    if one would prefer to skip kindergarten.
    Do you have statistics on that? And if it were true, that would tells us
    what? Majority rules?
    I beg to disagree. Most certainly needed. Indispensable and to the
    point. The more I think about it, the more life or dead issue it
    USENETwisely becomes.
    I've never seen FOAD by PE as 1st advice. Have you? It's reserved only
    for the obtuse && unteachable.

    Now I'll have to brace myself, because I'm pretty sure that PE is going
    to (justly) rebuke me for not being on topic.
    Osmo Saarikumpu, Oct 6, 2009
  16. John Ca

    optimistx Guest

    And you?
    optimistx, Oct 6, 2009
  17. ACK. For reasons now quite inexplicable to me, I had actually spent half
    the night explaining in detail to this luser where he f***ed up. And then I
    got this incredibly stupid response just before I went to bed. It just
    needed to be said for having a good night's sleep. (Not very logical of me,
    I know ...)
    As you wish:

    +-------------------+ .:\:\:/:/:.
    | PLEASE DO NOT | :.:\:\:/:/:.:
    | FEED THE TROLLS | :=.' - - '.=:
    | | '=(\ 9 9 /)='
    | Thank you, | ( (_) )
    | Management | /`-vvv-'\
    +-------------------+ / \
    | | @@@ / /|,,,,,|\ \
    | | @@@ /_// /^\ \\_\
    @x@@x@ | | |/ WW( ( ) )WW
    \||||/ | | \| __\,,\ /,,/__
    \||/ | | | (______Y______)



    (F'up2) PointedEars
    Thomas 'PointedEars' Lahn, Oct 6, 2009
  18. John Ca

    GTalbot Guest

    The OP wanted help and he provided quite a bit of useful details (not
    all, maybe not enough). With PointedEars, it quickly aggravated into
    verbal abuse.
    I do not think the OP had a bad initial post. It needed a few
    questions to be answered but that's it. I've seen much worse initial
    post from newbies.
    The OP stated twice that he was a newbie.
    You certainly understand what I mean by tone. Pedantic tone. Abrasive
    remarks. Talking down remarks. *That* tone.
    I have read the messages without any inferred tone. Many replies from
    PointedEars demonstrate lack of diplomacy and poor social skills. And
    a willingness to engage (fight) people over formalisms of all sorts.
    Over-excessively pointing people to the FAQ should be addressed one
    day. People shouldn't have to read 61 Kb just to post a question in
    This thread started with a question, need for assistance: it had
    already enough useful details (sufficient chunk of relevant code;
    browser and browser versions mentioned) to at least continue. It ended
    up into verbal abuse.

    You chose to reply. I am not responsible for your decisions, your
    typing, your freedom. Same thing with PointedEars: he chooses his
    words, he chooses to engage not perfect-from-the-start posting in
    here. He is abrasive and pedantic.

    I don't need a full program course in psychology to know that he is
    abrasive, nitpicking, unneedlessly pedantic. The way he replies, the
    words he chooses, the manners of addressing people reveal his social
    It is like that. FAQ section 1.3 has 7 links for more reading!
    And anyone posting for the first time a question in c.l.js will most
    likely not know that there is a FAQ to read before posting.
    Right here, you "sound" like PointedEars.

    I don't think the OP was obtuse, unteachable, narrow-minded or
    unwilling to compromise over some posting rules or some other points
    of formalism.
    There is no need whatsoever for verbal abuse in c.l.js. If you can't
    stand a post, then don't reply. If that is not in the FAQ (and related
    webpages), then it should be.

    GTalbot, Oct 6, 2009
  19. John Ca

    JR Guest

    There has been a 'poll' about TPE sometime ago:

    Unfortunately, to get on with TPE is like 'to carry a heavy burden up
    the hill'. The alternative is to killfile him - for those who dislike
    his antics.
    JR, Oct 6, 2009
  20. OK. I'll Think twice about sending mails at night.

    I'll try to refrain from posting things that make me look bad and take
    away from all the hard work I put into trying to help someone.
    Garrett Smith, Oct 7, 2009
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