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Searching for '\' with javascript

I wrote the following code to get just the filename without extension and path. I am running it in a browser.

<script type="text/javascript">
var str=new String("C:\Documents and Settings\prajakta\Desktop\substr.html");
document.write(str);
var beg=str.lastIndexOf("\");// **HERE IS THE PROBLEM IT DOESNT GIVE ME THE INDEX OF '\'**
 alert(beg);
var end=str.lastIndexOf (".");
 alert(end);
document.write("<br>"+str.slice(beg+1,end));
</script>

but the same code works if I replace '\' with another ex character. ('p'); im initializing var str for ex only, but in my application it is not always fixed. How can I add any body plz to Javascript, tell me what is the problem? n how to solve it?

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8 answers


You need to escape your backslash character. Use the following:

var beg=str.lastIndexOf("\\");

EDIT: Yes, it will give -1 unless you avoid backslashes in the original string :)



Use this:

var str=new String("C:\\Documents and Settings\\prajakta\\Desktop\\substr.html");

The backslash is a Javascript escape character - this means that characters following the backslash are special characters. So in your original line \ prajakta will be interpreted as '\ p' + 'rajakta', where '\ p' has a very different meaning. Thus, you need to use ' \\

' everywhere on every line.

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Read this article about javascript string escaping using backslash \



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"\"

is an escape character, try "\\"

Anyway, I would do it with regexes, just because I like them :)

var str=new String("C:\\Documents and Settings\\prajakta\\Desktop\\substr.html");
document.write(str);
document.write("<br>"+str.replace(/^.*\\/,"").replace(/\..*?$/,""));

Oh, and in testing I've seen that you also need to avoid backslashes in your test string!

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You need to escape "\" in most languages ​​because \ is an escape sequence. Perhaps Javascript is the same.

Try searching "\\"

(no space). Also, replace "C:\Docume..."

with "C:\\Documents..."

for the same reason

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Try

lastIndexOf("\\")
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The backslash is usually an escape character, so you'll have to type it twice when it happens on a string, i.e. your

var str=new String("C:\Documents and Settings\prajakta\Desktop\substr.html");

must read

var str=new String("C:\\Documents and Settings\\prajakta\\Desktop\\substr.html");

The point is that it is \D

interpreted by the javascript engine and will be replaced with the corresponding special character (in this case I don't believe there is a special character \D

(or 'p' or 's'), so it will be replaced simply D

and your string content will be

"C:Documents and SettingsprajaktaDesktopsubstr.html"

Go ahead, check it out with a simple

if (str == "C:Documents and SettingsprajaktaDesktopsubstr.html") alert("Doh! :)");

he should give you a warning.

Also, your

var beg=str.lastIndexOf("\");

must read

var beg=str.lastIndexOf("\\");

NTN.

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Before you insert a string into a variable, you must have escape(String)

it.

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in addition to what has already been said, "newline" is meaningless here.

var str="C:\\Documents and Settings\\prajakta\\Desktop\\substr.html";

and yes, regex is the way to go

fileName = str.match(/([^\\.]+)\.\w+$/)[1]
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