BP_041_en.md

Avoid modifications during DOM traversal

Identifiers

GreenIT	V2	V3	V4
43	43	41

Categories

Life cycle	Tiers	Responsible
3. Implementation	User/Device	Software Architect/Developer

Indications

Priority	Implementation difficulty	Ecological impact
4	4	4

Saved resources
Processor

Description

Modifying DOM (Document Object Model) elements while navigating through it can result in situations leading to greedy resource consumption, especially CPU cycles. Adding elements during DOM traversal might end up creating an infinite loop which will consume a large amount of resources. This kind of modification should be avoided when possible.

Example

Avoid :

<script>
     // jQuery notation
     $('a.extlink').each(function(el) {
         $(el).attr('rel','external nofollow');
     });
</script>

Validation rule

The number of ...	is equal to or less than
DOM element modifications performed when the same part of the DOM is traversed by JavaScript code	0