ifelse statement with iFrames

I have an iframe and i would like to make an if co开发者_StackOverflow社区ndition that if the iframe source is equal to a speciefied page a div should show:

Example

if(getElementById('iframe').src = 'someurl'){
getElementById('div').style.display. = 'block';
}

The Problem

I am not an expert in JS but when I use this script the iframe loads "someurl" automatically asoon as the main page is loaded, which I don't want, I want the div to be displayed when the iframe source changes to "someurl" via a link. The link is working fine and it changes the iframe src but the if statement isn't working.

• = is an assignment
• == is an equality test
• === is an equality test without type casting (and is generally prefered to ==

Use ===, not =.

Then you need to reference getElementById correctly. It is a method of the document object, not a global.

Use document.getElementById not getElementById

Then, you'll need to get rid of the trailing . character from your display property.

Then, assuming you want to update this when a link in the frame is followed and not just when a link in the current page is followed, you need to rerun the function periodically to see if it has changed.

setInterval(yourFunctionName, 5000); 

Then, since the page might move away from the URL you are looking for, you need to add an else statement

function yourFunctionName () {
    var div = document.getElementById('div'); /* Really? Your unique ID for a specific div is 'div'?! */
    if(document.getElementById('iframe').src === 'someurl'){
        div.style.display = 'block';
    } else {
      div.style.display = 'none';
    }

}

    if(document.getElementById('iframe').src == 'someurl'){
          document.getElementById('yourdiv').style.display = 'block';
    }

use == instead of = you are assign value to the src instead of checking for condition.

use == or ===

You have error in

if(getElementById('iframe').src = 'someurl')

= is assignment, but you should check condition. Use ==. You can swap condition, to eliminate errors, like this. Here is an example:

if('someurl' == getElementById('iframe').src)

The basick idea is than constant should be left part of comparision. And if you accidentally write assignment instead of comparison, i'll get more clear error.