querySelector vs getElementById

Get Element By Id

• It returns a node list which is live, meaning if you add or remove any element from the DOM the node list will update
• It is faster relative to the query selector methods

Query Selector

• It returns a node list which was available at the time of the execution

Also Read:

1. Applying floats and clearfix to block elements
2. simple css reset
3. Array filterUntil function implementation for javascript
4. Progressive enhancement vs Graceful degradation
5. Error: can not find module 'underscore'