Javascript how to remove parameter from URL sting by value?

Question

How to remove parameters with value = 3 from URL string?

Example URL string:

https://www.example.com/test/index.html?param1=4&param2=3&param3=2&param4=1&param5=3

Patrick Evans · Accepted Answer · 2018-08-23T02:42:28.067

2

If you are targeting browsers that support URL and URLSearchParams you can loop over the URL's searchParams object, check each parameter's value, and delete() as necessary. Finally using URL's href property to get the final url.

var url = new URL(`https://www.example.com/test/index.html?param1=4&param2=3&param3=2&param4=1&param5=3`)

//need a clone of the searchParams
//otherwise looping while iterating over
//it will cause problems
var params = new URLSearchParams(url.searchParams.toString());
for(let param of params){
   if(param[1]==3){
     url.searchParams.delete(param[0]);
   }
}
console.log(url.href)

edited Aug 23 '18 at 02:42

answered Aug 23 '18 at 02:03

Patrick Evans

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Thanks! I think it is better than regular expression. – mr.boris Aug 23 '18 at 02:10
@mr.boris see updated example, iterating over it and deleting at the same time will cause it to skip entries so you have to make a clone first and loop over the clone to prevent this problem (it is similar to iterating over [arrays and deleting](https://stackoverflow.com/questions/9882284/looping-through-array-and-removing-items-without-breaking-for-loop)) – Patrick Evans Aug 23 '18 at 02:44

CertainPerformance · Answer 2 · 2018-08-23T02:12:17.833

1

You could use a regular expression replace. Split off the query string and then .replace &s (or the initial ^) up until =3s:

const str = 'https://www.example.com/test/index.html?param1=4&param2=3&param3=2&param4=1&param5=3';
const [base, qs] = str.split('?');
const replacedQs = qs.replace(/(^|&)[^=]+=3\b/g, '');
const output = base + (replacedQs ? '?' + replacedQs : '');
console.log(output);

edited Aug 23 '18 at 02:12

answered Aug 23 '18 at 01:59

CertainPerformance

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Your output still shows `param5=3`. I though the OP wanted to remove this. – Tim Biegeleisen Aug 23 '18 at 02:00
@CertainPerformance Actually, your answer is little bit [incorrect](https://regex101.com/r/It5qAQ/1) – mr.boris Aug 23 '18 at 02:03
@mr.boris My mistake, think I fixed it now – CertainPerformance Aug 23 '18 at 02:09
Your solution still has a problem, because if _all_ the query parameters have a value of 3, it would still leave a dangling `?` at the end of the URL. [See here](http://rextester.com/MWF82876). – Tim Biegeleisen Aug 23 '18 at 02:11

score 1 · Answer 3 · answered Aug 23 '18 at 02:07

There is a way to do this with a single regex, using some magic, but I believe that would require using lookbehinds, which most JavaScript regex engines mostly don't yet support. As an alternative, we can try splitting the query string, then just examining each component to see if the value be 3. If so, then we remove that query parameter.

var url = "https://www.example.com/test/index.html?param1=4&param2=3&param3=2&param4=1&param5=3";
var parts = url.split(/\?/);
var params = parts[1].replace(/^.*\?/, "").split(/&/);
var param_out = "";
params.forEach(function(x){
    if (!/.*=3$/.test(x))
        param_out += x;
});

url = parts[0] + (param_out !== "" ? "?" + param_out : "");
console.log(url);

thank you. I think it is most supported method for browsers! — mr.boris, Aug 23 '18 at 02:19

Javascript how to remove parameter from URL sting by value?

3 Answers3