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JavaScript JavaScript and the DOM (Retiring) The Browser Environment Thinking Globally

Posted by igorzinken
igorzinken
1,284 Points

document.getElementsByTagName('p').style.background = 'yellow'

Hi,

I tried to do manipulate by TagName , as below but it didn't work document.getElementsByTagName('p').style.background = 'yellow' OR document.getElementsByTagName('p').style.backgroundColor = 'yellow'

what might be wrong? Thanks

2 Answers

Steven Parker
Steven Parker
231,236 Points
Steven Parker
Steven Parker
231,236 Points

The result of getElementsByTagName is a collection, not a single element, so it would not have a "style" property.

You can index the collection to access a single element. For example, if you wanted to alter the very first paragraph (index 0) on the page:

document.getElementsByTagName('p')[0].style.backgroundColor = 'yellow';
Joshua Bryant
Joshua Bryant
17,268 Points
Joshua Bryant
Joshua Bryant
17,268 Points

getElementsByTagName('p') will return a collection of all paragraph tags on the page. In order to change the background color of every paragraph tag on the page, you must loop through each paragraph tag individually and set it. 

for (var p in document.getElementsByTagName('p')) { 
    // Skip the collection elements that are not indexed by numbers, such as 'length'
    if (!isNaN(p) === true) {
        document.getElementsByTagName('p')[p].style.backgroundColor = 'yellow'; 
    }
}