Regex - Matching Only Part of the String

Question

Its part of an exercise and the task is:

If the first arg is only the url, then return the url + the second arg (which is a id number) //that works in my code
If the first arg (url) includes already the id-then exchange that Id with the second arg(Id) -for example http://www.google.com?ID=111 becomes http://www.google.com?ID=222

My code is wrong, happy about suggestions!

var first = "http://www.google.com?ID=111";
var second = "ID=222";

function searching(){
    var update="";
    if (arguments[0]==/^\w+@\w+\.com$/i){
        return arguments[0]+"?"+arguments[1];
    }
    else {
        update=arguments[0].match(/(\w+@\w+\.com) \?\w+\d/i);
    }
    return update + "?" +arguments[1]; 
}

searching(first, second);

Your regexp has a space before `\?`, but there's no space in the URL. — Barmar, May 24 '16 at 15:22
Why are you calling the function with arguments when it has no parameters? — Barmar, May 24 '16 at 15:23
You are explicitly scanning for .com domains. Is that part of the exercise? — le_m, May 24 '16 at 15:23
Why does your regexp have `@` in it? There's no `@` in the URL. — Barmar, May 24 '16 at 15:24

score 1 · Answer 1 · edited May 23 '17 at 12:31

1

You can't just compare a string to a regex with ==. Basically your choices are match, test, replace, and split. your regex btw has a \w when you wanted just a w, should be: /www\.\w+\.com$/i - I just shortened it even further. there's a million shades of regex validation when it comes to testing for valid URL in javascript. Generally, I think, you should just construct a "good enough" regex for your use case: here we just care if the query param is there, or not:

var first = "http://www.google.com?ID=111";
var second = "ID=222";
function searching(){
    var update="";
    if (/^.*\.com$/i.test(arguments[0])){ 
        //pattern just checks end of string to see if query param is present.
        return arguments[0]+"?"+arguments[1];
    }
    else {
        update=arguments[0].replace(/ID=\d+/, second); //
    }
    return update;
}
searching(first, second);

edited May 23 '17 at 12:31

Community

1
1

answered May 24 '16 at 15:33

Scott Weaver

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Thanks, can you explain if (/^.*\.com$/.test(arguments[0])){ and why (what I wrote): if (arguments[0]==/^\www.\w+\.com$/i){ is wrong? – learningcoding May 24 '16 at 15:41
Okay so I changed it to if (arguments[0].match(/^www\.\w+\.com$/i)){ update=arguments[0]+"?"+arguments[1]; } but thats wrong too?! – learningcoding May 24 '16 at 16:00
that's wrong. `match` return a match object, and would not perform the `replace` that you want. – Scott Weaver May 24 '16 at 16:06

score 0 · Answer 2 · answered May 24 '16 at 15:25

You could just check for the ? and if the first argument contain the sign '?' then get the first part (url) using .split('?')[0] and add second argument arguments[1], else just add the second argument directely to the first argument (url) :

function searching()
{
    if (arguments[0].indexOf('?')!=-1)
        return arguments[0].split('?')[0]+"?"+arguments[1];
    else 
        return arguments[0]+"?"+arguments[1];
}

Hope this helps.

Regex - Matching Only Part of the String

2 Answers2