Check whether a div exists and redirect if not

How do I check w开发者_Python百科hether a certain div exist on my page and if not, redirect the visitor to another page?

You will need to use JavaScript to be able to check if the element exists and do the redirect.

Assuming the div has an id (e.g. div id="elementId") you can simply do:

if (!document.getElementById("elementId")) {
    window.location.href = "redirectpage.html";
}

If you are using jQuery, the following would be the solution:

if ($("#elementId").length === 0){
    window.location.href = "redirectpage.html";
}

Addition:

If you need to check the content of divs for a specific word (as I think that is what you are now asking) you can do this (jQuery):

$("div").each(function() {
    if ($(this).text().indexOf("copyright") >= 0)) {
        window.location.href = "redirectpage.html";
    }
});​

Using jQuery you can check it like this:

if ($("#divToCheck")){ // div exists } else { // OOPS div missing }

or

if ($("#divToCheck").length > 0){
  // div exists
} else {
  // OOPS div missing
}

or

if ($("#divToCheck")[0]) {
  // div exists
} else {
  // OOPS div missing
}

What differenciate this particular div from others on the page ?

If it has an ID, you can to this with document.getElementById:

var div = document.getElementById('the-id-of-the-div');
if (!div) {
    location = '/the-ohter-page.html';
}

You can also check the content of the div:

var div = document.getElementById('the-id-of-the-div');
var html = div.innerHTML;

// check that div contains the word "something"
if (!/something/.test(html)) {
    location = '/the-ohter-page.html';
}

You can use jQuery for that

if ($("#mydiv").length > 0){
    // do something here
}

Read more here: http://jquery.com/

Edit: Fixed the error pointed out in the comment below. Sorry, busy day at work and got too trigger happy.