How to do an if/then in to handle if a Parameter isn't being passed to the api

Question

I have a SharePoint 2016 page that expects a parameter and dynamically builds the url for the API call based on that parameter.

But, I'm struggling with what/how to do an if/then in my ajax to handle if no parameter is sent to the page.

Is it even possible to do an if/then in the AddFeatureSuggestion function to change the url for the api call?

This is the specific line I'd like to be able to set in the if/then:

url: _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getbytitle('" + listName2 + "')/items?$filter=SitePath eq '/sites/" + siteUrlFromParameter + "'"

Here's my code so far:

function getUrlVars() {
            var vars = {};
            var parts = window.location.href.replace(/[?&]+([^=&]+)=([^&]*)/gi, function(m,key,value) {
            vars[key] = value;
                });
            return vars;
        }

        function getUrlParam(parameter, defaultvalue){
            var urlparameter = defaultvalue;
            if(window.location.href.indexOf(parameter) > -1){
            urlparameter = getUrlVars()[parameter];
        }
            return urlparameter;

function addFeatureSuggestion() {

        var siteUrlFromParameter = getUrlParam('Title', _spPageContextInfo.webAbsoluteUrl);

        $.ajax({
         url: _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getbytitle('" + listName2 + "')/items?$filter=SitePath eq '/sites/" + siteUrlFromParameter + "'",

        });

Answer 1

Yes you can do it like this:

var restEndpointUrl;
var siteUrlFromParameter = getUrlParam('Title', '');

if(siteUrlFromParameter) {
    //write code for setting URL when parameter is passed to your page
    restEndpointUrl = _spPageContextInfo.webAbsoluteUrl + "/_api/web/lists/getbytitle('" + listName2 + "')/items?$filter=SitePath eq '/sites/" + siteUrlFromParameter + "'"
} else {
    //handle case when the parameter is not passed to your page
} 
$.ajax({
    url: restEndpointUrl, 
    ... 
});