Javascript match and test returning null to DOI Regex expression

Question

I have been trying to find a way to recognize DOI on an input form to trigger a specific search. I found a DOI regular expression here and when I use it with Match or Test I got 'NULL' and Error as result

function checkDOI(string){
        //Redundant. I know 
        var testKey = String(string);
        var DOIpattern = '\b(10[.][0-9]{4,}(?:[.][0-9]+)*/(?:(?!["&\'<>])\S)+)\b';

        var found = DOIpattern.test(testKey);
        console.log("found", found + " DOI "+ testKey);
        return found
      }
checkDOI("10.1016.12.31/nature.S0735-1097(98)2000/12/31/34:7-7")

I got this error DOIpattern.test is not a function

Then if I change the found.test for MATCH var found = DOIpattern.match(testKey);

The result is NULL

Does anybody can tell me what I am doing wrong?

Thank in advance!

Answer 1

test is a method of RegExp class and not of String. To correct, create a RegExp object using the constructor and call the test method on it.

function checkDOI(string) {
  //Redundant. I know 
  var testKey = String(string);
  var DOIpattern = '\b(10[.][0-9]{4,}(?:[.][0-9]+)*/(?:(?!["&\'<>])\S)+)\b';

  var found = new RegExp(DOIpattern).test(testKey);
  console.log("found", found + " DOI " + testKey);
  return found
}

checkDOI("10.1016.12.31/nature.S0735-1097(98)2000/12/31/34:7-7")

As long as your RegExp string is correct, the input should match.

Answer 2

create a RegExp object using the constructor and call the test method on it.

Thank you! your response worked. Just in case someone else is looking for a regular expression the one I am using is not properly written, so I cut it to this

\b(10[.][0-9]{4,}(?:[.][0-9]+)*\b/g

And the final version looks like this:

 checkDOI(string){
        var DOIpattern = new RegExp(/\b(10[.][0-9]{4,}(?:[.][0-9]+)*)\b/g);
        // var DOIpattern = ;
        var found = DOIpattern.test(testKey);
        console.log("found", found + " DOI "+ testKey);
        return found
      }