WEB Authoring - Javascript: prosince 2015

čtvrtek 3. prosince 2015

How to check if cookies are enabled

The navigator object has the attribute cookieEnabled that returns true if the cookies are enabled in the browser. Find a simple example bellow.

<HTML>
<HEAD>
  <SCRIPT>
    function checkCookies(){
    window.alert("Are cookies enabled? "+(navigator.cookieEnabled?"Yes":"No"));
    }
  </SCRIPT>
</HEAD>
<BODY>
  <BUTTON onclick="checkCookies()">Check cookies</BUTTON>
</BODY>
</HTML>

středa 2. prosince 2015

Periodical Call of Javascript Function using SetTimeout

The following example shows how to set up a periodical function call of JavaScript function inside an html page.


<html>
<head>

<script>
var imageRefs = ["pict1.png","pict2.png","pict3.png"];
var counter = 0;

(function changeImage(){
  
 image = document.getElementById("image1");
 if(image != null) {
   image.src = imageRefs[counter];
   counter = (counter + 1) % 3;
   }

 setTimeout(changeImage,2000);

})();
</script>

</head>
<body>

<img id="image1" src="pict1.png" />

</body>

</html>

Here is the working example:

Change picture on click

A following simple example shows how to write the html page with pictures that rotate on mouse click event.

<html>
<head>

<script>
function changeImageOnClick(){
    image=document.getElementById("image1");
    
        if(image.src.indexOf("pict1.png")<0)
            image.src="pict1.jpg";
        else
            image.src="pict2.jpg";
}
</script>
</head>
<body>

<img src="pict1.png" id="image1" onclick="changeImageOnClick()"/>

</body>

Here is the working example: