Javascript replace & changing sting from a vriable

Question

I have a URL https://example.com/fullimg.php?eid=1&pgno=&pdate=2022年12月24日,

I want to create a next and previous button. If the user clicks on the next button he will redirect to pgno=1 means the next page. If he clicks on the next button again he will be redirected to pgno=2 and so on if he clicks next again he will be redirected to pgno=3 here the pdate is dynamic and changes every day.

I have tried this

 let url = window.location.href;
 if (url.includes("pgno=")) {
 url = url.replace("pgno=", "pgno=2");
 } else if (url.includes("pgno=2")) {
 url = url.replace("pgno=", "pgno=3");
 }
 console.log(url);
 window.location.replace(url);

Also I have tried this

 let url = window.location.href;
 if (url.includes("pgno=")) {
 url = url.replace("pgno=", "pgno=2");
 } 
 if (url.includes("pgno=2")) {
 url = url.replace("pgno=", "pgno=3");
 }
 console.log(url);
 window.location.replace(url);

For both it's only executing first condition not the 2nd one. After clicking on the next button it's going to pgno=2 but after that when I am clicking next it's still reloading and redirecting to pgno=2

How can I solve it?

I have solved it, thanks to @Unmitigated

this is the function,

 function Next2() {
 let params = new URLSearchParams(location.search);
 // get the value of pgno
 let pgno = +params.get('pgno');
 // check if pgno is less than or equal to 12
 if (pgno <= 11) {
 // go to next page
 params.set('pgno', pgno + 1);
 location.search = params;
 }
 }

And here is the previous function

 function Prev1() {
 let params = new URLSearchParams(location.search);
 // get the value of pgno
 let pgno = +params.get('pgno');
 // check if pgno is greater than 1
 if (pgno > 1) {
 // go to previous page
 params.set('pgno', pgno - 1);
 location.search = params;
 }
 }

• Louys Patrice Bessette: Nice reading here

Answer 1

Use URLSearchParams to facilitate handling query strings.

let params = new URLSearchParams(location.search);
// go to next page
params.set('pgno', +params.get('pgno') + 1);
location.search = params;

• Mohammad Fathi Rahman: Thanks, working. But how can I stop it when it reaches 12? And will it work for previous button if I use params.set('pgno', +params.get('pgno') -1); and stop when pgno is 1?
• Unmitigated: @MohammadFathiRahman You would need to manually check for the page number being equal to 1 or 12.