This is a simple question I think.
I am trying to search for the occurrence of a string in another string using regex in JavaScript like so:
var content ="Hi, I like your Apartment. Could we schedule a viewing? My phone number is: ";
var gent = new RegExp("I like your Apartment. Could we schedule a viewing? My", "g");
if(content.search(gent) != -1){
alert('worked');
}
This doesn't work because of the ?
character....I tried escaping it with \
, but that doesn't work either. Is there another way to use ?
literally instead of as a special character?
This question is related to
javascript
regex
literals
You need to escape it with two backslashes
\\?
See this for more details:
http://www.trans4mind.com/personal_development/JavaScript/Regular%20Expressions%20Simple%20Usage.htm
You should use double slash:
var regex = new RegExp("\\?", "g");
Why? because in JavaScript the \
is also used to escape characters in strings, so: "\?" becomes: "?"
And "\\?"
, becomes "\?"
You can delimit your regexp with slashes instead of quotes and then a single backslash to escape the question mark. Try this:
var gent = /I like your Apartment. Could we schedule a viewing\?/g;
Whenever you have a known pattern (i.e. you do not use a variable to build a RegExp), use literal regex notation where you only need to use single backslashes to escape special regex metacharacters:
var re = /I like your Apartment\. Could we schedule a viewing\?/g;
^^ ^^
Whenever you need to build a RegExp dynamically, use RegExp
constructor notation where you MUST double backslashes for them to denote a literal backslash:
var questionmark_block = "\\?"; // A literal ?
var initial_subpattern = "I like your Apartment\\. Could we schedule a viewing"; // Note the dot must also be escaped to match a literal dot
var re = new RegExp(initial_subpattern + questionmark_block, "g");
And if you use the String.raw
string literal you may use \
as is (see an example of using a template string literal where you may put variables into the regex pattern):
const questionmark_block = String.raw`\?`; // A literal ?
const initial_subpattern = "I like your Apartment\\. Could we schedule a viewing";
const re = new RegExp(`${initial_subpattern}${questionmark_block}`, 'g'); // Building pattern from two variables
console.log(re); // => /I like your Apartment\. Could we schedule a viewing\?/g
_x000D_
A must-read: RegExp: Description at MDN.
Source: Stackoverflow.com