Javascript conflict over string.replace method

Question

I am using a javascript code to display an ad in my page . The javascript code for the corresponding ad display is as shown below :

var ad = {
    encode: function(str) {
        return escape(this._utf8_encode(str));
    },

    _utf8_encode: function(str) {
        str = str.replace(/\r\n/g, "\n");
        var utftext = "";

        for (var n = 0; n < str.length; n++) {

            var c = str.charCodeAt(n);

            if (c < 128) {
                utftext += String.fromCharCode(c);
            }
            else if ((c > 127) && (c < 2048)) {
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
            }
            else {
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);
            }

        }
        return utftext;
    }
}

var partnerId = "b7241ebe72fa74ce";
var siteId = "11738";

var targetparams = new Array();
targetparams['ad_platform'] = "ros";
var targetparams_str = "";
for (var key in targetparams) {
    if (targetparams_str != "") {
        targetparams_str += "||";
    }
    targetparams_str += ad.encode(key) + "=>" + ad.encode(targetparams[key]);
}
targetparams_str = ad.encode(targetparams_str);

var m3_u = 'http://ads.admarvel.com/fam/javascriptGetAd.php';
var m3_r = Math.floor(Math.random() * 99999999999);
document.write("<scr" + "ipt type='text/javascript' src='" + m3_u);
document.write("?partner_id=" + partnerId);
document.write('&amp;site_id=' + siteId);
document.write('&amp;target_params=' + targetparams_str);
document.write('&amp;version=1.5');
document.write('&amp;language=javascript');
document.write('&amp;format=wap');
document.write('&amp;cb=' + m3_r);
document.write("'><\/scr" + "ipt>");

The above code is inside a element in the HTML body. Now in my page I want to include an external js library protoaculous.1.8.2.min.js and when I place this js file in the head , somehow , my ad disapperars , but as soon as I remove the external library , the ad is displayed .

The outline of my page is as below :

<head>
<script type="text/javascript" src="http://www.ectnews.com/shared/ajax/protoaculous.1.8.2.min.js"></script>
<body>
    <div>
        //Javascript code for the ad display
    </div>
</body>

Following are the links to the scenario I have created in my test server :

Non-Working html :

http://m.smartdevicemedia.com/test_external_js.htm

Working html :

http://m.smartdevicemedia.com/test_external_js_good.htm

Could you indent less? Can't see half of your code.

Dave Newton
– Dave Newton

2011-09-20 12:19:28 +00:00
Commented Sep 20, 2011 at 12:19 — Dave Newton
– Dave Newton, Commented Sep 20, 2011 at 12:19

Pointy · Accepted Answer · 2011-09-20 12:27:58Z

1

I suspect that the problem is here:

var targetparams = new Array();
targetparams['ad_platform'] = "ros";
var targetparams_str = "";
for (var key in targetparams) {
    if (targetparams_str != "") {
        targetparams_str += "||";
    }
    targetparams_str += ad.encode(key) + "=>" + ad.encode(targetparams[key]);
}

The Prototype library adds a bunch of methods to the Array prototype, and your "for ... in" loop will see those. There's no reason for "targetparams" to be an Array instance, however. It should just be an object:

var targetparams = {};

In fact, from that code above there's no reason for "targetparams" to even exist. You could simply initialize the string to the single key that you've actually got hard-coded there in the lines above the loop:

var targetparams_str = ad.encode("ad_platform") + "=>" + ad.encode("ros");

It also seems very odd that you'd re-encode the whole string after building up the string from encoded pieces.

answered Sep 20, 2011 at 12:27

Pointy

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1 Comment

josh.trow Over a year ago

You may have something here - when I look at the values of targetparams_str in both pages, I get ad_platform=>ros|| in the 'bad' page (see my answer for why) and ad_platform%3D%3Eros in the 'good' page. Notice that the good page doesn't have the '||' at the end.

josh.trow · Accepted Answer · 2011-09-20 12:25:02Z

0

Check your dev console:

Uncaught TypeError: Object function (C,B){var A=0;try{this._each(function(E){C.call(B,E,A++)})}catch(D){if(D!=$break){throw D}}return this} has no method 'replace'

test_external_js.htm:45

This Line:

string = string.replace(/\r\n/g,"\n");

Now as to WHY it does this...

answered Sep 20, 2011 at 12:25

josh.trow

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5 Comments

deGee Over a year ago

ya...I have seen that...Even , I am surprised, somehow the external js script modifies the methods of the String class? Even if you comment this line it will throw a error in the immidiate next line containing the string object.

josh.trow Over a year ago

@debaShish: Well, did you try changing the name to something neutral, like 'theValue'?

deGee Over a year ago

ya...also tried that ...but it gave the error like : "Object doesn't support this method or property"

josh.trow Over a year ago

@debaShish: Of course, it all makes sense now! Pointy has it - Prototype adds all kinds of stuff to Objects, and 'for...in' loops break if you don't add something like if (!targetparams.hasOwnProperty(key)) continue. The code works for the first iteration through the loop, but the second time in, it calls '_utf8_encode' with one of the Prototype addons - which is an Object, not a String.

deGee Over a year ago

thanks buddy , I also saw the error . I shouldn't be calling the '_utf8_encode' function with targetparams[key] as it is an Object here. Thanks for pointing this out.

epascarello · Accepted Answer · 2011-09-20 12:27:30Z

0

You can not put that code in the head with document.writes out html markup tags.You would put the code where you want the ad to appear on the page.

<head>
</head>
<body>
    <div>
        <script type="text/javascript" src="yourAdCode.js"></script>
    </div>
</body>

answered Sep 20, 2011 at 12:27

epascarello

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