JavaScript
Is it better to return null or undefined?
Determine the dimensions of elements
clientWidth, clientHeight
The size of the displayed content, including padding, without scrollbars and borders.
scrollWidth, scrollHeight
The actual size of the content, regardless of how much of it is currently visible.
offsetWith, offsetHeight
The width and height of an element, including borders, without margins. Ignores scaling.
getBoundingClientRect()
Returns an object with the left=x, top=y, right, bottom, width, and height
properties of an element, including borders, without margins. Considers scaling, returns the
rendered size.
See also: MDN, Determining the dimensions of elements
Dynamically add an element
const element = document.createElement("div")
element.appendChild(document.createTextNode("Loram Ipsum"))
context.appendChild(element)Read CSS variables
window.getComputedStyle(document.documentElement).getPropertyValue('--css-variable')