I have a problem replace certain words started with #. I have the following code
var x="#google",
eval("var pattern = /" + '\\b' + x + '\\b');
txt.replace(pattern,"MyNewWord");
when I use the following code it works fine
var x="google",
eval("var pattern = /" + '\\b' + x + '\\b');
txt.replace(pattern,"MyNewWord");
it works fine
any suggestion how to make the first part of code working
ps. I use eval because x will be a user input.
The problem is that \b represents a boundary between a "word" character (letter, digit, or underscore) and a "non-word" character (anything else). # is a non-word character, so \b# means "a # that is preceded by a word character" — which is not at all what you want. If anything, you want something more like \B#; \B is a non-boundary, so \B# means "a # that is not preceded by a word character".
I'm guessing that you want your words to be separated by whitespace, instead of by a programming-language concept of what makes something a "word" character or a "non-word" character; for that, you could write:
var x = '#google'; // or 'google'
var pattern = new RegExp('(^|\\s)' + x);
var result = txt.replace(pattern, '$1' + 'MyNewWord');
Edited to add: If x is really supposed to be a literal string, not a regex at all, then you should "quote" all of the special characters in it, with a backslash. You can do that by writing this:
var x = '#google'; // or 'google' or '$google' or whatever
var quotedX = x.replace(/[^\w\s]/g, '\\$&');
var pattern = new RegExp('(^|\\s)' + quotedX);
var result = txt.replace(pattern, '$1' + 'MyNewWord');
$ has a special meaning in regular expressions -- it means "end of string" -- so the regex /(^|\s)$google/ is never matched by anything. To match an actual dollar sign, you'd have to "quote" it with a backslash: /(^|\s)\$google/. If you're expecting x to be a literal string, and you want to find occurrences of exactly it, then you'd want to start by quoting all of its special characters. Here, I'll update my answer . . .Make you patter something like this:
/(#)?\w*/
If you want to make a Regular Expression, try this instead of eval:
var pattern = new RegExp(x);
Btw the line:
eval("var pattern = /" + '\\b' + x + '\\b');
will make an error because of no enclose pattern, should be :
eval("var pattern = /" + '\\b' + x + '\\b/');
How about
var x = "#google";
x.match(/^\#/);
eval()these! Usenew RegExp('\\b' + x + '\\b')eval