I found several similar questions, but it did not help me. So I have this problem:
var xxx = "victoria";
var yyy = "i";
alert(xxx.match(yyy/g).length);
I don't know how to pass variable in match command. Please help. Thank you.
7 Answers
Although the match function doesn't accept string literals as regex patterns, you can use the constructor of the RegExp object and pass that to the String.match function:
var re = new RegExp(yyy, 'g');
xxx.match(re);
Any flags you need (such as /g) can go into the second parameter.
1 Comment
Christian C. Salvadó
+1, this is the preferred way, BTW, if the argument passed to the
match method is not a RegExp object, internally the RegExp constructor will be invoked using that value, so you can use a string pattern, e.g.: "a123".match("\\d+")[0] === "123";You have to use RegExp object if your pattern is string
var xxx = "victoria";
var yyy = "i";
var rgxp = new RegExp(yyy, "g");
alert(xxx.match(rgxp).length);
If pattern is not dynamic string:
var xxx = "victoria";
var yyy = /i/g;
alert(xxx.match(yyy).length);
1 Comment
flaky
You get a imaginary downvote for using w3schools instead of MDN! developer.mozilla.org/en/docs/Web/JavaScript/Reference/…
Example. To find number of vowels within the string
var word='Web Development Tutorial';
var vowels='[aeiou]';
var re = new RegExp(vowels, 'gi');
var arr = word.match(re);
document.write(arr.length);
answered Nov 8, 2014 at 12:07
Sarvar Nishonboyev
13.2k11 gold badges80 silver badges78 bronze badges
Comments
For example:
let myString = "Hello World"
let myMatch = myString.match(/H.*/)
console.log(myMatch)
Or
let myString = "Hello World"
let myVariable = "H"
let myReg = new RegExp(myVariable + ".*")
let myMatch = myString.match(myReg)
console.log(myMatch)
1 Comment
Arindam Sarkar
it is helpful but when i use let myString = "Tata Nexon EV Tata" let myVariable = "Tata" let myReg = new RegExp("\b"+myVariable , "g") let myMatch = myString.match(myReg) console.log(myMatch) not working
for me anyways, it helps to see it used. just made this using the "re" example:
var analyte_data = 'sample-'+sample_id;
var storage_keys = $.jStorage.index();
var re = new RegExp( analyte_data,'g');
for(i=0;i<storage_keys.length;i++) {
if(storage_keys[i].match(re)) {
console.log(storage_keys[i]);
var partnum = storage_keys[i].split('-')[2];
}
}
Comments
Below is an example of a simple and effective way to mock 'like' operator in JS. enjoy!
const likePattern = '%%i%%%%%a';
const regexp = new RegExp(likePattern.replaceAll('%','.*'),"i");
console.log("victoria".match(regexp));
Comments
xxx.match(yyy, 'g').length
1 Comment
Christian C. Salvadó
This will work only in Firefox, and it isn't even documented. The specification states that the
String.prototype.match method expects only one argument. Using the RegExp constructor, as @Chris suggests is the preferred way.
SyntaxError: Invalid regular expression: /c++/: Nothing to repeat