使用JavaScript访问div的子节点

Question

I have created a div using the following code...

var bannerBox = document.createElement("div");
bannerBox.id = "bannerBox";

...and a second div as follows...

var bannerAd = document.createElement("div");
bannerAd.className = "bannerAd";

The above divs have been created in one function. Now in another function I tried to access the first div as follows...

var allAds = document.getElementById("bannerBox").childNodes; 

...but it produces this error: uncaught error cannot read property childnodes of null

Answer 1

You have to actually put the bannerBox div in the document, by passing it into appendChild or insertBefore on some element that's in the document (such as document.body ):

document.body.appendChild(bannerBox);

(But it can be any element in the document, doesn't have to be body .)

Once it's in the document, you can retrieve it by id the way you've shown.

And of course (this isn't the problem you're having but it could be the next problem), for bannerBox to have any child nodes (eg, for childNodes not to be an empty NodeList ), you need to put something in it. From your variable names, I'm thinking probably you'd want to put bannerAd in it, for instance:

bannerBox.appendChild(bannerAd);