Comments on: BUJS #1 – getParameterByName

By: Ifthikhan Nazeem

Ifthikhan Nazeem — Tue, 01 Nov 2011 09:12:15 +0000

@Felix Your code will have issue if the value of a key is a base64 encoded string.

By: Todd Wheeler

Todd Wheeler — Sun, 11 Sep 2011 23:06:48 +0000

@James,

I wanted to pass a link through the query string,… but think instead that it would make more sense to parse through the query on the receiving page to create a link.

What I’m trying to do is to send the name of an image.jpg through the query string, and then provide a link to a hi-res version of the image on the receiving page.

By: Álvaro G. Vicario

Álvaro G. Vicario — Mon, 11 Jul 2011 06:12:41 +0000

@Bush Tag: It’s pretty normal that JavaScript code won’t pass HTML validation, isn’t it?

By: Bush_Tag

Bush_Tag — Tue, 07 Jun 2011 09:35:14 +0000

Iam getting these errors in w3c validation in the “&” plz can anybody help

Line 166, Column 27: xmlParseEntityRef: no name

var match = RegExp(‘[?&]’ + name + ‘=([^&]*)’)

By: James

James — Thu, 03 Mar 2011 07:55:00 +0000

@Felix, Andy E. mentioned that idea and FWIW, if we were talking about potential applications of the function I would agree, but the purpose of BUJS is simply to take ugly code and make it prettier and more efficient — even if it is fighting the wrong battle.

@Alvaro, I agree–it should be supported natively.

@Joss, thanks! 🙂

By: Joss Crowcroft

Joss Crowcroft — Thu, 03 Mar 2011 04:08:30 +0000

Love the article dude – you could also have picked up on the three var ; declarations right after each other that I guess could have been combined!

I wouldn’t have spotted those crazy optimisations though. As soon as I see regexes my eyelids feel really heavy.

By: Felix

Felix — Wed, 02 Mar 2011 15:36:28 +0000

I’m usally generating an JS-object out of the parameters. That makes many things a whole lot easier – and prevents me from using RegExps. Besides, if you plan to look up multiple parameters, my solution will perform better. Just to illustrate the main idea (the code hasn’t been tested):

var querystring = (function(query){
    var qs = {},
        params = query.split("&"),
        parts;
    for(var i = 0; i < params.length; i++){
        parts = params[i].split("=");
        qs[ parts[0] ] = parts[1] ? parts[1] : "";
    }
 
    return qs;
})(document.location.search ? document.location.search.substring(1) : "");

By: Álvaro G. Vicario

Álvaro G. Vicario — Wed, 02 Mar 2011 15:25:26 +0000

@James – Nice bit, thank you. I’ve always wondered why JavaScript lacks a native RexExp method to quote a literal.

By: Andy E

Andy E — Wed, 02 Mar 2011 00:07:52 +0000

@James,

That’s also a very nice workaround. Looking forward to BUJS #2 – maybe I’ll join in if I come across some horrendously ugly code 🙂

By: James

James — Tue, 01 Mar 2011 23:50:53 +0000

@Andy, I agree 100%. To be honest, when I did this I wasn’t thinking so much about application but simply about code clarity/readability and micro-efficiency.

@Everyone, if you care, and want to use this for your app, please use Andy’s answer or at least add some caching in, e.g.

var getParameterByName = (function(){
 
    var c = {};
 
    return function getParameterByName(name) {
 
        name = String(name).replace(/[.*+?|()[]{}\]/g, '\$&');
 
        if (name in c) { return c[name]; }
 
        var match = RegExp('[?&]' + name + '=([^&]*)')
                        .exec(window.location.search);
 
        return match && (
            c[name] = decodeURIComponent(match[1].replace(/+/g, ' '))
        );
 
    };
 
}());