Parse Query String by pure JavaScrirpt

Here is a snipped I wrote today to parse Query String by pure JavaScript. Some people uses different JavaScript libraries. But from my older days when I used to parse GET parameter by perl I had a habit of writing this algorithm. I just translated it to JavaScript.

Here goes the code.

function getUrlParts(url){
// url contains your data.
var qs = url.indexOf("?");
    if(qs==-1) return [];
    var fr = url.indexOf("#");
    var q="";
    q = (fr==-1)? url.substr(qs+1) : url.substr(qs+1, fr-qs-1);
var parts=q.split("&");
var vars={};
for(var i=0;i<parts.length; i++){
var p = parts[i].split("=");
        if(p[1]){
vars[decodeURIComponent(p[0])] = decodeURIComponent(p[1]);
        }else{
            vars[decodeURIComponent(p[0])] = "";
        }
}
// vars contain all the variables in an array.
return vars;
}

Iterate through each valid calendar days

If you develop software like me, you may face a scenario where you need to iterate through calendar days.  These are specially needed in event management application or any other application that has some sorts of daily tracker. The main point is you want to iterate through dates.

For example, If the current date is “February 28th 2001”, next date will be  “March 1st 2001”. Obviously not “February 29th 2001”. If the current date is “February 28th 2004”, next date will be “February 29th 2004”, Not “March 1st 2004”.  Yes, that’s quite tricky.  So how do you achieve it in programming?

The solution is to use time function families found in standard C header file time.h. The main idea is to first create the time you want to show by mktime(). This is the initial time. To advance to the next day/hour/min/sec/month just convert the resultant value of mktime() to struct tm structure by localtime() or gmtime(). Then add 1 day/hour/min/sec/month to struct tm structure. Use this structure to create time again by mktime().

The above strategy works because of the following lines from manual.

     In addition to computing the calendar time, mktime() normal-
     izes  the  supplied tm structure. The original values of the
     tm_wday and tm_yday components of the structure are ignored,
     and the original values of the other components are not res-
     tricted to the ranges indicated in  the  definition  of  the
     structure

Here is a sample code that iterates through the first 200 dates from epoch.


#include <time.h>;
#include <stdio.h>;

int main(){
    struct tm *lt;
    int i=200;
    time_t t=1;  // first second on epoch

    while(i--){
        lt = localtime(&t);
        printf("%s\n", asctime(lt));
        lt->tm_hour+=24; // adding 1 day = 24 hours
        t = mktime(lt);
    }
    return 0;
}

If you are working with other language you may wonder if this will apply to your language. The good news is most language has wrapper for C routines.  May be the name is different. But  most probably you have it. Just see the manual.  Same technique will work on other language too.

Data extraction from external url via php made easy

How many times you extracted data from other website to include in your site? I guess its many times. In this web 2.0 era we all mix up different type of contents to make our own. Sometimes you grab data from youtube.com, sometimes amazon.com and then you create a mesh up. All these things need little bit of data parsing knowledge. Also you need to interact with an http resource. Many PHP coders does it by curl, DOMDocument etc extensions. This job is quite tedious. To resolve this problem I created a class long time ago. Now I put them on http://github.com/shiplu. The classes I am talking about can be found on http://github.com/shiplu/dxtool.

“dxtool” stands for data extraction tools. Its very easy to use. Here I dump the README file from github.

Requirement

  • php5
  • php5-curl extension
  • php5-json extension (already included with php5)

Features

  • Extract Data from any http resource
  • Use simple regular expression to extract data
  • Hassle free http transaction
  • Supports cookie (via curl)
  • Can cache http response

Here is an example on how to use it.

<?php
require 'DataExtractor.php';
require 'WebGet.php';
$google_new_feed = 'http://news.google.com/news?pz=1&cf=all&ned=in&hl=en&output=rss';
$w = new WebGet();
$content = $w->requestContent($google_new_feed);
$dx = new DataExtractor($content);
$dx->titles = '|title>([^<]+)</title|a';
$dx->rsstitle = '|title>([^<]+)</title|';
$data = $dx->extractArray();
print_r($data);
?>

If you run it you’ll see this output. Output will be different as google news rss will change over time

Array
(
    [titles] => Array
        (
            [0] => Top Stories - Google News
            [1] => Top Stories - Google News
            [2] => Draft of Lokpal Bill discussed informally at cabinet meet - Hindustan Times
            [3] => cabinet clears Food Security Bill - Hindustan Times
            [4] => Obama hails Havel's 'moral leadership' and 'dignity' - AFP
            [5] => Philippines struggles to cope after storm leaves 650 dead - Telegraph.co.uk
            [6] => Civil nuclear liability rules balanced, India to Russia - Hindustan Times
            [7] => 'Include Muslims, expand OBC quota' - Hindustan Times
            [8] => Sadhbhavana's success answer to Gujarat detractors: Narendra Modi - Daily News & Analysis
            [9] => Female protestor's beating sparks Egypt outrage - Telegraph.co.uk
            [10] => Romney says US withdrawal from Iraq 'precipitous' - AFP
            [11] => Come clean on Chidambaram's alleged favours to ex-client: BJP to Centre - The Hindu
        )

    [rsstitle] => Top Stories - Google News
)