css-box-model
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1.2.1 • Public • Published

css-box-model 📦

Get accurate and well named CSS Box Model information about a Element.

Build Status npm dependencies Downloads per month min minzip

Any time you are using Element.getBoundingClientRect() you might want to consider using css-box-model instead to get more detailed box model information.

Usage

// @flow
import { getBox } from 'css-box-model';
 
const el: HTMLElement = document.getElementById('foo');
const box: BoxModel = getBox(el);
 
// profit

Installation

## yarn 
yarn add css-box-model
 
# npm 
npm install css-box-model --save

The CSS Box Model

the box model

Box type Composition
Margin box margin + border + padding + content
Border box border + padding + content
Padding box padding + content
Content box content

This our returned BoxModel:

export type BoxModel = {|
  // content + padding + border + margin
  marginBoxRect,
  // content + padding + border
  borderBoxRect,
  // content + padding
  paddingBoxRect,
  // content
  contentBoxRect,
  // for your own consumption
  borderSpacing,
  paddingSpacing,
  marginSpacing,
|};
 
// Supporting types
 
// This is an extension of DOMRect and ClientRect
export type Rect = {|
  // ClientRect
  topnumber,
  rightnumber,
  bottomnumber,
  leftnumber,
  widthnumber,
  heightnumber,
  // DOMRect
  xnumber,
  ynumber,
  // Rect
  centerPosition,
|};
 
export type Position = {|
  xnumber,
  ynumber,
|};
 
export type Spacing = {
  topnumber,
  rightnumber,
  bottomnumber,
  leftnumber,
};

API

getBox

(el: HTMLElement) => BoxModel

Use getBox to return the box model for an element

withScroll

(original: BoxModel, scroll?: Position = getWindowScroll()) => BoxModel

This is useful if you want to know the box model for an element relative to a page

const el: HTMLElement = document.getElementById('app');
const box: BoxModel = getBox(el);
const withScroll: BoxModel = withScroll(box);

You are welcome to pass in your own scroll. By default we we use the window scroll:

const getWindowScroll = (): Position => ({
  x: window.pageXOffset,
  y: window.pageYOffset,
});

calculateBox

(borderBox: AnyRectType, styles: CSSStyleDeclaration) => BoxModel

This will do the box model calculations without needing to read from the DOM. This is useful if you have already got a ClientRect / DOMRect and a CSSStyleDeclaration as then we can skip computing these values.

const el: HTMLElement = document.getElementById('app');
const borderBox: ClientRect = el.getBoundingClientRect();
const styles: CSSStyleDeclaration = window.getComputedStyles(el);
 
const box: BoxModel = calculateBox(borderBox, styles);

AnyRectType allows for simple interoperability with any rect type

type AnyRectType = ClientRect | DOMRect | Rect | Spacing;

createBox

({ borderBox, margin, border, padding }: CreateBoxArgs) => BoxModel

Allows you to create a BoxModel by passing in a Rect like shape (AnyRectType) and optionally your own margin, border and or padding.

type CreateBoxArgs = {|
  borderBox: AnyRectType,
  margin?: Spacing,
  border?: Spacing,
  padding?: Spacing,
|};
const borderBox: Spacing = {
  top: 10,
  right: 100,
  left: 20,
  bottom: 80,
};
const padding: Spacing = {
  top: 10,
  right: 20,
  left: 20,
  bottom: 10,
};
 
const box: BoxModel = createBox({ borderBox, padding });

Utility API

Functions to help you interact with the objects we provide

getRect

(spacing: AnyRectType) => Rect

Given any Rect like shape, return a Rect. Accepts any object that has top, right, bottom and right (eg ClientRect, DOMRect);

const spacing: Spacing = {
  top: 0,
  right: 100,
  bottom: 50,
  left: 50,
};
 
const rect: Rect = getRect(spacing);
 
console.log(rect);
 
/*
{
  top: 0,
  right: 100,
  bottom: 50,
  left: 50,
  width: 100,
  height: 50,
  x: 0,
  y: 0,
  center: { x: 50, y: 50 },
}
*/

expand

Used to expand a Spacing

(target: Spacing, expandBy: Spacing) => Spacing;
const original: Spacing = {
  top: 10,
  left: 11,
  right: 21,
  bottom: 22,
};
 
const expandBy: Spacing = {
  top: 1,
  left: 2,
  right: 3,
  bottom: 4,
};
 
const expanded: Spacing = expand(original, expandBy);
 
console.log(expanded);
 
/*
{
  // pulled back
  top: 8,
  left: 8
  // pushed forward
  bottom: 22,
  right: 22,
}
*/

shrink

Used to shrink a Spacing

(target: Spacing, shrinkBy: Spacing) => Spacing;
const original: Spacing = {
  top: 10,
  left: 10,
  right: 20,
  bottom: 20,
};
 
const shrinkBy: Spacing = {
  top: 2,
  left: 2,
  right: 2,
  bottom: 2,
};
 
const smaller: Spacing = shrink(original, shrinkBy);
 
console.log(smaller);
 
/*
{
  // pushed forward
  top: 12,
  left: 12
  // pulled back
  bottom: 18,
  right: 18,
}
*/

Package Sidebar

Install

npm i css-box-model

Weekly Downloads

2,232,669

Version

1.2.1

License

MIT

Unpacked Size

31.6 kB

Total Files

10

Last publish

Collaborators

  • alexreardon