在match的正则表达式上指示的Javascript match（）字符串字母

Question

I have a variable which contain a string and I want to return only the letters from regular expression (“b” and “D”) or any letter that I indicate on regular expression from match().

var kk = "AaBbCcDd".match(/b|D/g); 
     kk.forEach(function(value,index){
     console.log(value,index) 
});

My problem is that regular expression I think because is returning b and D but the index is not the index from kk variable and I'm not really sure, why ... so if someone can help me a little bit because I stuck

Answer 1

The match method from javascript only returns an array with the given match: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/String/match

You would need to implement a new function which will loop through all characters of your string and return the given index of the matches. This method could use the function search from String.prototype: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/String/search

Answer 2

You have to write a new function to get the index of the matched regex like a sample below:-

var re = /bar/g,
  str = "foobarfoobar";
while ((match = re.exec(str)) != null) {
  alert("match found at " + match.index);
}

Hope this will help you

Answer 3

Actually this is the answer :

var kk = "AaBbCcDd".match(/B?d?/g); 
     kk.forEach(function(value,index){
     console.log(value,index) 
});

if someone will encounter this scenario ...

The match() regular expresion B?d? will return an array indicating the position of "B" and "d" of the initial array kk.