Add parameters on href url with javascript and with specific conditions

Question

I have some problem with my javascript functions. I want to add some parameters to the href url when it cliked. For example I want to add ?param=1 in href url when it's clicked. But before add some parameters I want to check if the url in href is http://example.com and that parameters not contain ?param=1 . After it checked and the url is http://example.com and not contain ?param=1 , I want to add the ?param=1 in that url. Why I want to check first before adding the parameters? It's because I don't want to add the parameters in any url but just in specific url which I want.

This is what I do till now:

window.addEventListener("click", function(e) {
    var href = e.target.getAttribute("href");
    if(href) {
        location.href = href + "?param=1";
        e.preventDefault();
    }
});​

But, I don't know how to check and make specific conditions if the href is http://example.com . Please anybody know how to do this could help me. Thanks before.

Answer 1

Check the queryString and see if it has the param1 value, if it does not then append it.

var url = new URL("http://www.example.com?param=1"); //window.location.href

if (url.searchParams.get('param'))
{
  console.log("Param exists");
}
else
{
   console.log("Param does not exist")
   url + "?param=1"
   console.log(url);
}

Answer 2

 window.addEventListener("click", function(e) { e.preventDefault(); var href = e.target.getAttribute("href"); console.log(href); if(href) { if(href.indexOf("param=1")==-1){ href = href + "?param=1"; console.log(href); // location.href = href; }else{ href = href + "?param=2"; console.log(href); // location.href = href; } // } }); 

 <a href="http:example.com?param=1">click</a> 

The index to start the search in the string or object. It will return -1 if there is no search found.

Answer 3

 $(document).ready(function(){ var href = "www.example.com?param=1"; if(href.indexOf("www.example.com") >=0 && href.indexOf("param=1") >= 0) { alert('Url has given words'); //location.href = href + "?param=1"; // e.preventDefault(); } }) 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <div>Check URL</div> 

Answer 4

Check it out:

 window.addEventListener("click", function(e) { const href = e.target.getAttribute("href"); if(href) { console.log(href.includes('?param=1')); // You can do whatever you want based on this condition e.preventDefault(); } }); 

 <a href='http://example.com/'>Link 1</a> <br/><br/> <a href='http://example.com/?param=1'>Link 2</a> 

Answer 5

Learn about indexOf for check if values exist in the querystring

 var str="Hello world!" document.write(str.indexOf("Hello") + "<br />") document.write(str.indexOf("World") + "<br />") document.write(str.indexOf("world")) 

• The indexOf () method is sensitive to case sensitive.
• If the string value that is to be retrieved does not appear, the method returns -1