How to search in array

First of all: Both definitions of your urls variable are JSON:

1. first definition is an array of Strings in JSON notation
2. second definition is an array of objects, each consisting of one property url as a string.

In order to search through the second one, you need to iterate over the objects array explicitly and compare the property explicitly (as one approach):

var found = false;
for ( var n = 0; n < urls.length; n++ )
{
    if ( urls[n].url == window.location.hostname )
    {
       /// do something

       found = true;
       break;
    }
}
if ( !found )
{

  // do something other

}

Or may be

if(urls.map(function(obj){ return obj.url}).indexOf(window.location.hostname)>0){
  // do something ...
}
else {
  window.location.href = 'redirect url';
}

Using lodash version 4 or later, you could do this:

if (_(urls).map('url').includes(window.location.hostname)) {
  // do something...
} else {
  window.location.href = 'redirect url';
}

When it comes to arrays of objects you cannot access elements like what you have done in your code. You have to use a loop to travers through the elements or an inbuilt functions like filter,map.Without using inbuilt functions you can do something like this to get your work done.

function to search for a particular url in the array

function findURL(array,url) {

    for (var i = 0; i < array.length; i++) {

        if (array[i].url == url) {
            return i;
        }
    }
    return -1;
}

Put below piece of code where you want to check the condition

var urls = [
    {
        'url':'url1'
    },
    {
        'url':'url2'
    },
];

if(findURL(urls,window.location.hostname) > -1){
    //do something ..
}else{
    window.location.href = 'redirect url';
}

There are some answers which describe how to apply filter and map methods in your scenario.Therefore I think i don't want to put those in my answer.

If you use jquery there is a function called grep which returns an array of items found.

var urls = [
    {
        'url':'url1'
    },
    {
        'url':'url2'
    },
];

var result = $.grep(urls, function(e){ return e.url == window.location.hostname; });

if (result.length == 0) { // nothing found

   window.location.href = 'redirect url';

} else if (result.length == 1) { // one item found

      //do something ..
      // you can access the found item by result[0].foo if you want

} else { // multiple items found
  
}