Get Query String Parameters with JavaScript

Query string parameters have been incredibly useful on the server side since the internet took liftoff, but it wasn't until AJAX-driven web apps became popular that we relied too much on them on the client side. Not only do we grab parameter values but we also modify them dynamically with the History API, so these parameters play a major role outside of the initial page load.

We've always been able to get the full query string via the window.location.search property:

console.log(window.location.search);
// "?post=1234&action=edit"

...but in a world of setters, getters, and JSON, there must be a better way to get values than parsing a string, right? After years of ugly string parsing, there's a better way: URLSearchParams Let's have a look at how we can use this new API to get values from the location!

// Assuming "?post=1234&action=edit"

var urlParams = new URLSearchParams(window.location.search);

console.log(urlParams.has('post')); // true
console.log(urlParams.get('action')); // "edit"
console.log(urlParams.getAll('action')); // ["edit"]
console.log(urlParams.toString()); // "?post=1234&action=edit"
console.log(urlParams.append('active', '1')); // "?post=1234&action=edit&active=1"

URLSearchParams also provides familiar Object methods like keys(), values(), and entries():

var keys = urlParams.keys();
for(key of keys) { 
  console.log(key); 
}
// post
// action

var entries = urlParams.entries();
for(pair of entries) { 
  console.log(pair[0], pair[1]); 
}

URLSearchParams reminds me a lot of the classList API -- very simple methods yet very useful.

JavaScript Fallback

While URLSearchParams is ideal, not all browsers support that API. There's a polyfill available but if you want a tiny function for basic query string parsing, the following is a function stolen from the A-Frame VR toolkit which parses the query string to get the key's value you'd like:

경축! 아무것도 안하여 에스천사게임즈가 새로운 모습으로 재오픈 하였습니다.
어린이용이며, 설치가 필요없는 브라우저 게임입니다.
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function getUrlParameter(name) {
    name = name.replace(/[\[]/, '\[').replace(/[\]]/, '\]');
    var regex = new RegExp('[\?&]' + name + '=([^&#]*)');
    var results = regex.exec(location.search);
    return results === null ? '' : decodeURIComponent(results[1].replace(/\+/g, ' '));
};

With the function above, you can get individual parameter values:

getUrlParameter('post'); // "1234"
getUrlParameter('action'); // "edit"

Anyways, enjoy this function -- you'll find yourself needing it more than you think!

[출처] https://davidwalsh.name/query-string-javascript