Slash escape in javascript

Question

function slashEscape(strVar){
    var retVal = strVar;
    retVal = retVal.replace(/\\/g,"\\\\");
    return retVal;
}

I use that function to escape the slashes in a certain string. But the result is not right.

var str = slashEscape("\t \n \s");

It will result to "s" instead of "\\t \\n \\s"

Answer 1

When the string constant "\\t \\n \\s" is instantiated to a JavaScript string, it transforms \\t to a tab character, the \\n to a new line, and \\s to a s .

That's why you can't replace \\ with \\\\ because as far as JavaScript is concerned, there is no \\ character. There is only a tab character, a new line, and an s .

---

By the way, the result of slashEscape("\\t \\n \\s"); is not "s" . It's actually :

"    
s"

Which is a tab in the first line, a new line, then an s.

Answer 2

To add on to what Mark Gabriel already said, it is the parser , and not any runtime code, that transforms escape sequences within your string. By the time the string is passed to your function, the parser has already removed the backslashes--they don't exist.