Ajax Shopping Cart Knowledge Summary

Steps to run Ajax:

var info= "";
Creating objects
var xhr=new xmlhttprequest ();
Handling Return Values
Xhr.onreadystatechange = function () {

Determine if loading is complete
if (xhr.readystate = = 4) {
if (xhr.responsetext== "success") {
Location.href= "index.php";
}else{
Alert ("Login" +xhr.responsetext);
}
}
}
Initiating a request
info= "uid=" +uid+ "&pwd=" +PWD;

Get Pass Value
Xhr.open ("Get", "php/login_php.php?") +info);

Post Pass Value
Xhr.open ("Post", "php/login_php.php");

Get Value Header text
Xhr.setrequestheader (' Content-type ', ' application/x-www-form-urlencoded ');
Send data
Xhr.send (info);

Session

You can store values in the Session object. The information stored in the session object is valid within the sessions and session scopes.

Example:

<% session ("username") = "Janine" session ("age") = 24%>
Pass value of Session:

Example:

$_session["UID"] = UID;
$_session["name"] = $PWDARR [1];//user name
$_session["account"] = $PWDARR [2];//user balance

Session Application:
Session_Start (); //must be used on the page header

String conversion Issues

Converts a two-dimensional array that is queried in the data to a string

Querying the database

$sql = "SELECT * from Fruit";

Execute SQL statement
$ret = $db->query ($sql);

Convert the result to a two-dimensional array
$SPARR = $ret-Fetch_all ();
Convert a two-dimensional array to a string
$str = "";
foreach ($spArr as $v) {

Traverse two-dimensional array, get the one-dimensional array $v, divide the one-dimensional array with implode, the result is added to itself, and each one-dimensional array is divided by ^
$str. =implode (",", $v). " ^";
}

Remove the excess ^
Echo substr ($str, 0,-1);

break the string into arrays: explode () function

Example:

<?PHP$STR = "Hello World". I Love shanghai! "; Print_r (Explode ("", $str));? >

To combine array elements into strings: implode () function
Example:

<?php$arr = Array (' Hello ', ' world! ', ' I ', ' love ', ' shanghai! '); echo Implode ("", $arr);? >

Convert a string to a two-dimensional array

Splitting a string into a one-dimensional array with split and delimiter ^

var temp=str.Split("^");
var arr=[];

Loop to add data from a one-dimensional array to an array
for (Var i=0;i<temp.length;i++) {
Arr[i]=temp[i].split (",");
Console.log (arr);
}

Use of values in Ajax:

Get the value of the PHP page when it is finished processing

var str = Xhr.responsetext;
Show (str);

Define a parameter to accept the value passed over

function Tshow (str) {}

A convenient way to convert a two-dimensional array to a one-dimensional array and then to a string:

Convert a two-dimensional array to a one-dimensional array
foreach ($spAttr as $v) {
$V =join (",", $v);
$arr [] = $V;

}
Convert a one-dimensional array to a string
Echo (Join ("^", $arr));
?>

Ajax Shopping Cart Knowledge Summary