Parameters of a line (GET) in Javascript

Practically on each site it is possible to see the links containing in parameters after a sign "?", for example, http: // some.site.com/? id=1. Usually the server script is engaged in processing of such parameters, but sometimes there is a necessity to learn{find out} these parameters inside JavaScript. How it to make, and there will be a story today.

What are, so-called, GET-parameters? Actually is simply a line of the address, but it is accepted, what if in URL-S there is a symbol "?", all symbols after him  are parameters. The treatment of parameters - is standard: first there is a name of a variable, then a symbol "=", then value of a variable, variables are divided{shared} by a symbol "¿". To learn{find out} the current address in JavaScript it is possible having read value window.location. Parsit` a line after "?" It is necessary in two passes: first to break into groups "peremennaja=znachenie", and then already to break into components.

Splitting of a line of parameters is facilitated by that, that in JavaScript there is a special line function - split () which result will be a file of lines. That her  to use, all over again it is necessary to create object String as the given function is a method of this object. It is done{made} simply:

someVar = new String (" some text ");

Then we divide a line on podstroki:

someArray = someVar.split ("x");

Where "x" - a symbol of division of a line on podstroki. To find in line any symbol, it is necessary to use one more line function - indexOf ():

someVar.indexOf ('? ');

Input in the theory is finished. We shall start practice. I have decided, that all GET-variable should be stored{kept} in two separate global files: one stores{keeps} names, another - values. Unfortunately JavaScript does not support associative files, therefore we shall use the way specified by me. Also it is necessary to save quantity{amount} of GET-variable. Certainly, always it is possible to call function of calculation of the size of a file, but stilisticheski my method is better. And so, global variables and files:

var _GET_Keys; // Meanwhile an empty file

var _GET_Values;

var _GET_Count = 0; // elements while no

var _GET_Default = "

Value of a variable _GET_Default will be explained later. Further I shall create function get_parseGET () which will be parsit` URL and to create files with variables. Right at the beginning function creates object String and checks in him presence of a symbol "?":

get = new String (window.location);

x = get.indexOf ('? ');

if (x! =-1)

{

// Here there will be a basic code

}

else;

Further we cut out the part of the line which is taking place after the found symbol:

l = get.length;

get = get.substr (x+1, l-x);

Now we divide a line into groups "peremennaja=znachenie", we calculate total of variables and we are prepared to sozdainju necessary files:

l = get.split (' and ');

x = 0;

_GET_Count = l.length;

_GET_Keys = new Array (_GET_Count);

_GET_Values = new Array (_GET_Count);

And in summary we divide{share} the received groups on two files with names of variables and their values:

for (i in l)

{

get = l [i] .split (' = ');

_GET_Keys [x] = get [0];

_GET_Values [x] = get [1];

x ++;

}

In the given example the design for.. in, touching all elements of a file is used. Syntax of the given design:

for (key in array)

{

// Your actions

}

Where key - the name of a key which will be chosen from a file array. In a body of a cycle to the current element it is possible bduet to address array [key].

The second function from library - get_fetchVar (key), allows to learn{find out} value of the set GET-variable. Works simple pereborom a file _GET_Keys. If the key is not found, returns value _GET_Default which was mentioned above. I want to notice, that value _GET_Default is not so necessary for changing in the library - if necessary, it can be made in your HTML-code:

<script language = "JavaScript"> _GET_Default = " tra la la "; </script>

Right at the end of a script the call get_parseGET () follows; and on it the library comes to an end.