Sunday, 04 May 2014 11:02

Some useful javascript

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Some useful javascript
Create an XML HTTP Request (XHR) object
  1. function create_XMLHttpRequest() { //create new XHR object

  2.   if (window.XMLHttpRequest)

  3.   {// code for IE7+, Firefox, Chrome, Opera, Safari

  4.     xmlhttp=new XMLHttpRequest();

  5.   } else {// code for IE6, IE5

  6.     xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

  7.   }

  8.   return xmlhttp;

  9. }
 
 
Send request to Server and receive response from server
  • Get replay from php web server: serverResponseInfo=httpGetRequest("http://domain/myReply.php")
  • Read content from a text file: serverResponseInfo=httpGetRequest("myTextFile.txt")
  • Read content from a text file: document.getElementById("myDiv").innerHTML=loadXMLDoc("myTextFile.txt");
function httpGetRequest(url)
{
   xmlhttp= create_XMLHttpRequest();
   xmlhttp.open("GET",url,false);
   xmlhttp.send();
   return xmlhttp.responseText;
}
 
 
Check if file exist
  • To check a file if exist in www root directory: fileExists("/settings.xml")
  • To check a file if exist in the current directory: fileExists("settings.xml")
  1. function fileExists(filename) {

  2.     xmlhttp= create_XMLHttpRequest(); //create new XHR object

  3.     if(!xmlhttp) return false;

  4.     try

  5.     {

  6.         xmlhttp.open("HEAD", filename, false);

  7.         xmlhttp.send(null);

  8.         return (xmlhttp.status==200) ? true : false;

  9.     }

  10.     catch(er)

  11.     {

  12.         return false;

  13.     }

  14. }
 
 
Load an XML file using XML HTTP Request
Eg. loadXML("settings.xml")
  1. function loadXML(XML_filename) {

  2.   xmlhttp= create_XMLHttpRequest();

  3.   xmlhttp.open("GET",XML_filename ,false);

  4.   xmlhttp.send();

  5.   return xmlhttp.responseXML;

  6. }
 
 
Convert XML to string
  1. function xmlToString(xmlDoc){

  2.   if(xmlDoc.xml){

  3.     // MSIE

  4.     xmlString = xmlDoc.xml;

  5.   }else{

  6.     xmlString = (new XMLSerializer).serializeToString(xmlDoc);

  7.   }

  8.   return xmlString;

  9. }
 
 
Create a string based on date
Example of output: 2014_0502
  1. function createString_accordingDate() {

  2.   var today = new Date(); 

  3.   var dd = today.getDate(); 

  4.   var mm = today.getMonth()+1;//January is 0! 

  5.   var yyyy = today.getFullYear(); 

  6.   if(dd<10){dd='0'+dd} ;

  7.   if(mm<10){mm='0'+mm}; 

  8.   return (yyyy + "_" + mm + dd); 

  9. }
.
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Published in Tutorials
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