JavaScript: get and set URL hash parameters?

If you want to parse a hash URL:

var hash = window.location.hash.substr(1);

var result = hash.split('&').reduce(function (res, item) {
    var parts = item.split('=');
    res[parts[0]] = parts[1];
    return res;
}, {});

That way, if you have this: http://example.com/#from=2012-01-05&to=2013-01-01

It becomes: {'from': '2012-01-05', 'to':'2013-01-01'}

As @Dean Stamler notes in the comments, dont forget the empty starting object. }, {});

Now to set a hash URL:

window.location.hash = "from=2012-01-05&to=2013-01-01";

As for getting parameters... how about this solution:

var myUrl = new URL(window.location.href.replace(/#/g,"?"));
var param_value = myUrl.searchParams.get("param_name");

Wish u luck!

You can set the hash with:

window.location.hash = "new value";

and (in newer browsers) listen to changes with:

window.addEventListener("hashchange", function () {
});

If you need to support browsers that don't support "hashchange" you'll want to use code that other people have written, such as jquery's history plugin.

The other answers don't address the problem

I got a way easier approach:

Copy over current hashparameters to a dummy URL as searchParameters. Now you can treat the hash parameters like search-parameters and copy them back afterwards:

Simple function

function setOrUpdateHashParameter( hashParameterName, hashParameterValue ) {
    let theURL              = new URL('https://dummy.com');             // create dummy url
    theURL.search           = window.location.hash.substring(1);        // copy current hash-parameters without the '#' AS search-parameters
    theURL.searchParams.set( hashParameterName, hashParameterValue );   // set or update value with the searchParams-API
    window.location.hash    = theURL.searchParams;                      // Write back as hashparameters
}

For Multiple Params:

const href = window.location.href;
const params = href.split('?')[1];

// Be sure url params exist
if (params && params !== '') {
    const result = params.split('&').reduce(function (res, item) {
        const parts = item.split('=');
        res[parts[0]] = parts[1];
        return res;
    }, {});
}

Therefore, when href=https://www.example.net/page.html#/page1?foo=bar&token=123abc the result will evaluate to {foo: "bar", token: "123abc"}.

This structure requires that the URL has the question mark ? before the params, an equal sign = between the variable key and value, and a & between each key/value pair.

For get only:

const startingUrl = 'https://stackoverflow.com/questions/23699666/javascript-get-and-set-url-hash-parameters#state=XXX&b=YYY'
const myUrl = new URL(startingUrl);
const hash = new URLSearchParams(myUrl.hash.substring(1))
hash.get('state'); // XXX
hash.get('b'); // YYY

This is my solution

arr = location.search.replace('?', '').split('&').map(x => x.split('=')).map(x => {
    let keyName = x[0];
    let val = x[1];
    let object = {};
    object[keyName] = val;
    return object;
});

obj = {}

arr.forEach(function(x) {
    let key = Object.keys(x)[0];
    obj[key] = x[key];
});

console.log(obj);

Basicaly with location.search we obtain the right part of a url, after the path (the query params with).

location.search also returns the '?' character, replace with white space, then split whit '&', map and split with '=', for obtain un array like

[['term', 'hello'], ['lang', 'es']]

Then, assemble the object as you wanted

arr = "?safe=active&source=hp&ei=c4Q8XcOPFd3F5OUP7e242Ag&q=hola&oq=hola&gs_l=psy-ab.3..0l5j0i131j0l2j0i131j0.1324.1667..1798...1.0..0.264.744.1j3j1......0....1..gws-wiz.....10..35i39.-_FkFlX_Muw&ved=0ahUKEwiDlaTgytXjAhXdIrkGHe02DosQ4dUDCAU&uact=5".replace('?', '').split('&').map(x => x.split('=')).map(x => {
    let keyName = x[0];
    let val = x[1];
    let object = {};
    object[keyName] = val;
    return object;
});

obj = {}

arr.forEach(function(x) {
    let key = Object.keys(x)[0];
    obj[key] = x[key];
});

console.log(obj);

Based upon Maart's answer here is a version which returns the edited URL rather than applying the change to the current window.

function setHashParam(url, name, value) {

    // Create URL objects for the url we want to change and a dummy url (requires a polyfill for IE)
    var urlObj = new URL(url);
    var dummyObj = new URL('https://dummy.com');

    // Copy current hash-parameters without the '#' as search-parameters
    dummyObj.search = urlObj.hash.substring(1);

    // Set or update value with the searchParams-API (requires a polyfill for IE)
    dummyObj.searchParams.set(name, value);

    // Write back as hashparameters
    urlObj.hash = dummyObj.searchParams;

    return urlObj.href;
}

Note that for this answer (and Maart's) to work in IE they require polyfills for the URL constructor and the search params API.