strip two named querystring params from url using regex and replace in javascript

Question

I have a url like:

http://example.org/someparam=asdfadfsadf&lmnop=Lasda:sdf&radParam=dfadfs&qrstu=asfasdf:asaasd

I have this regex:

/(&|\?)(lmnop|qrstu)=.*?(&|$)/

But I want to match both not just the first?

The desired result is the url with the two querystring params and their values removed:

http://example.org/someparam=asdfadfsadf&radParam=dfadfs

@Mandy8055 the regex you suggested only matches the first? thanks! — billy jean
– billy jean, Commented Jul 3, 2020 at 13:54
If you want to replace the groups with different values, you might check for the value of each group. See ideone.com/cT45xR — The fourth bird
– The fourth bird, Commented Jul 3, 2020 at 14:11
@Mandy8055 You already have given a good answer, feel free to add or adjust it. — The fourth bird
– The fourth bird, Commented Jul 3, 2020 at 14:40

score 2 · Accepted Answer · 2020-07-03 15:01:52Z

2

1st approach without using regex:

Proposed Idea:

1. Split the string on & symbol.
2. Filter out those elements of the split string in step 1 which starts with lmnop= or qrstu=.
3. Join again on & symbol.

Please find the sample implementation below:

let string = `http://example.org/someparam=asdfadfsadf&lmnop=Lasda:sdf&radParam=dfadfs&qrstu=asfasdf:asaasd`;
console.log(
// Step 1
string.split("&").
// Step 2
filter(el => !(el.startsWith("lmnop=") || el.startsWith("qrstu="))).
// Step 3
join("&")
);

2nd Approach Using regex:

You may try:

&(?:lmnop|qrstu)=(.*?)(?=&|$)

Explanation of the above regex:

& - Matches & literally.
(?:lmnop|qrstu) - Represents a non-capturing group matching lmnop or qrstu.
= - Matches = literally.
(.*?) - Lazily matches everything till the end or &.
(?=&|$) - Represents a positive look-ahead which asserts end or &.

You can find the demo of the above regex in here.

const regex = /&(?:lmnop|qrstu)=(.*?)(?=&|$)/gm;
const str = `http://example.org/someparam=asdfadfsadf&lmnop=Lasda:sdf&radParam=dfadfs&qrstu=asfasdf:asaasd`;
const subst = ``;

// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);

console.log(result);

edited Jul 3, 2020 at 15:01

answered Jul 3, 2020 at 13:53

user7571182

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3 Comments

billy jean Over a year ago

The first solution does work but how can I get the remaining string rather than the extracted querystrings? The regex matches the first but not both.

billy jean Over a year ago

Yes I want to remove those two querystrings and their values while leaving the rest of the url intact.. no extra & etc. Thanks!

user7571182 Over a year ago

Thanks to @Thefourthbird for suggesting a beautiful enhancement in the mentioned regex.

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