Why does document.write("...") break my code?

Question

I'm trying to get the following Javascript work (it should be an embedded survey from formstack.com that shows up on specific days). However, when I try to view it all I get displayed is the string (without the quotes) "'); }" What is wrong?

<head>
<script type="text/javascript">

var theDate = new Date();
var dayOfWeek = theDate.getUTCDay();

// Returns true if the restaurant is open
function isOpen()
{
    //I'll fill this in later, for now, return true
    return true;
}
</script>

</head><body>
<script type = "text/javascript">
if(isOpen())
{
document.write('<script type="text/javascript" src="http://www.formstack.com/forms/js.php?1134414-uqmj2UXxEw-v2"></script>');
}
</script>
</body>

this does work, describe your problem... (What is the error, in what browser etc...) most of the time when you inject JS to the HTML you need to give it some time so the browser can interpret it.. — meo, Nov 06 '11 at 00:10

score 2 · Answer 1 · answered Nov 06 '11 at 00:10

You can't have a string containing '</script>' inside a SCRIPT element. Consider loading additional scripts like so:

var script = document.createElement( 'script' );
script.src = 'http://www.formstack.com/forms/js.php?1134414-uqmj2UXxEw-v2';
document.body.appendChild( script );

Your preferred JavaScript library probably contains a dedicated function for this. For instance, I use jQuery, where it's done like so:

$.getScript( 'http://www.formstack.com/forms/js.php?1134414-uqmj2UXxEw-v2' );

score 2 · Accepted Answer · answered Nov 06 '11 at 00:10

2

Don't have a </script> tag in your string, that ends the script tag.

document.write('<scr'+'ipt type="text/javascript" src="http://www.formstack.com/forms/js.php?1134414-uqmj2UXxEw-v2"></scr'+'ipt>');

answered Nov 06 '11 at 00:10

Guffa

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So why do you break up the ` – Jared Farrish Nov 06 '11 at 00:13
@JaredFarrish: Just to be on the safe side. It works simply because `` is not interpreted as an ending tag for the script. – Guffa Nov 06 '11 at 00:27
Just wondering... Why does JS interpret a script tag in a string as the ending tag for the calling statement? (Which is what I think you're saying, right?) – Jared Farrish Nov 06 '11 at 00:36
@Guffa I believe it's the constucte `` that has to be guarded against, per spec, but this is likely guarded to only need to protect against `` in modern browsers. ` – Nov 06 '11 at 00:44
1

@JaredFarrish: Because the HTML tags are parsed before the script. – Guffa Nov 06 '11 at 01:11

score 0 · Answer 3 · edited Nov 06 '11 at 00:10

0

I've heard stories of javascript failing to execute inside document.write... try breaking it up:

document.write("script type = " + "text/javascript" + "src='http://www.formstack.com/forms/js.php?1134414-uqmj2UXxEw-v2'>" + "/script");

(greater and less than signs removed, you should know where to put them)

edited Nov 06 '11 at 00:10

Jared Farrish

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answered Nov 06 '11 at 00:09

Techboy6601

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"You should know where to put them" - Huh? – Jared Farrish Nov 06 '11 at 00:10

score -1 · Answer 4 · answered Nov 06 '11 at 01:26

I wonder if the / of is being see as the escape character. Something that you can try is

String s = @"...." where .... is the text.

The @ tells the compiler to treat everything in "'s as a literal. I know that this works in both C# and Java. I am not 100% sure about javascript.

Why does document.write("...") break my code?

4 Answers4

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