Wildcard Match Anything with Period Test Issue

JavaScript
1

Tell us what’s happening:

Your code so far


let exampleStr = "The sun is out today.";
let unRegex = /.un/g; // Change this line
let result = unRegex.test(exampleStr);
console.log(exampleStr.match(unRegex));
console.log(result); 
exampleStr = "Seven days without a pun makes one weak.";
console.log(exampleStr.match(unRegex));
console.log(result);

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:67.0) Gecko/20100101 Firefox/67.0.

The above string examples will not pass the challenge test, yet they do log properly to the console. Befuddled.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/regular-expressions/match-anything-with-wildcard-period

2

Do you have a question?

3

Re-read the lesson. Sometimes it’s the small things. Did they tell you to use the global flag?

4

Yes. The code that I had written for this challenge, when tested with :

let exampleStr = "The sun is out today.";
exampleStr = "Seven days without a pun makes one weak.";
console.log(exampleStr.match(unRegex));
console.log(result);

The log reads in the console:

sun //as a string
true //as a boolean

pun //as a string
true //as a boolean

yet the challenge tests for those sentences does not clear.
I’m curious as to why.

5

As @Roma pointed out, you want to be careful when applying the global flag. Look at how the .test() method works with a global regex:

6

I did use global and the wildcard identifier.

7

Why would the global designation cause issues in these cases? There was also only one match in each string so the boolean could not be flipped.

8

Don’t do that

If the regex has the global flag set, test() will advance the lastIndex of the regex. A subsequent use of test() will start the search at the substring of str specified by lastIndex ( exec() will also advance the lastIndex property). It is worth noting that the lastIndex will not reset when testing a different string.

1 Like
9

Thanks for the lesson. Is there documentation that I can view with regard to this characteristic.

10

In my previous post there is linked the documentation on the test method, it is the source of my quote