How to check if the URL contains a given string?

When a simple true or false will do

Specify targeted string, let's say "franky" for instance:

if (window.location.href.includes("franky")) {
    console.log("'Franky' spotted in the URL! Is he involved in any suspicious activity?"); // CSI: URL
}
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jQuery – for those with exquisite taste

With jQuery ready to save the day:

$(document).ready(function() {
    if(window.location.href.indexOf("franky") != -1) { // -1 basically means 'Franky is currently MIA in the URL'
        alert("'Franky' is gracing us with his presence in the URL");
    }
});
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Ensure to include jQuery in your HTML for a fine dinner with jQuery:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
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Regular Expressions - it isn’t as difficult as it sounds

You can treat "franky" as a movie star having his première with Regular Expressions:

if (/franky/.test(window.location.href)) { // Regular Expressions extend a Red Carpet to 'Franky'
    console.log("'Franky' is shining in the URL!");
}
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When your browser wears vintage

Stick to indexOf() for ninth planet of the Solar system aka legacy browser-support:

let urlString = window.location.toString(); // Converting to String (or becoming fluent in URLish)
let containsString = urlString.indexOf("franky") != -1; // when Franky decides to leave, he leaves -1 in his wake
console.log(containsString);
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Mystery of Query Strings with URLSearchParams

Unraveling Query Strings

Investigate if a specific "search" is hanging around the Query string:

let params = new URLSearchParams(window.location.search);
let spiedParam = params.has("search"); // 'search' parameter behaving suspiciously in the URL
console.log(spiedParam);
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Snooping Parameter Values

Or snoop on value of a suspect named "search":

let value = params.get("search");
console.log(value); // Evident that 'search' haunts the URL in disguise
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Overcoming Hurdles

Race against the Clock (dress rehearsal)

Ensure your code doesn't start checking the URL without eating its breakfast (load):

window.onload = function() {
    if(window.location.href.includes("franky")) {
        alert("'Franky', you can't hide in the URL anymore.");
    }
};
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Cap Sensitive includes()

The includes() method is quite a stickler for UPPER case and lower case. If you are easy-going, opt for toLowerCase():

let lowerCaseUrl = window.location.href.toLowerCase();
console.log(lowerCaseUrl.includes("franky".toLowerCase())); // true, now 'Franky' can't play the 'disguise-in-Uppercase' card anymore
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Dealing with Tricky Hash values

If your strings like 'em hash tags (#):

console.log(window.location.hash.includes("#franky")); // true if "#franky" is a part of the tinsel party of the URL hash
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