stevekinney

Web Performance

Requirements

• You need to have the latest version of Node. Preferably, you're using 9.8.0, but the latest LTS should work as well.
• You should have npx installed using npm install -g npx.
• Install the React Developer Tools.

Repositories

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

tnguyen14

When you modify a file in your repository, the change is initially unstaged. In order to commit it, you must stage it—that is, add it to the index—using git add. When you make a commit, the changes that are committed are those that have been added to the index.

git reset changes, at minimum, where your current branch is pointing. The difference between --mixed and --soft is whether or not your index is also modified. So, if we're on branch master with this series of commits:

- A - B - C (master)

HEADpoints to C and the index matches C.

--soft