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    code width: 6.2rem; height: 6.2rem; border-width: .3rem; margin: 0.3rem 0.2rem;
      | box1
      | box2
      | box3


                html, body
  margin: 0
  padding: 0

  font-size: 16px;

  position: relative
  display: flex
  flex-direction: column 
  margin: auto
  max-width: 30rem
  //height: 75vh

  display: flex
  align-items: center
  justify-content: center
  padding: 1.5rem 0
  height: 100%
  margin: 0.3rem 0.2rem
  background: #f8f5f0
  border: .3rem solid #2ba4bb
  width: 6.2rem
  height: 6.2rem
  display: flex
  align-items: center
  justify-content: center

  margin-top: 1rem

  color: #e83e8c
  background: #e8ebf1
  border-radius: .2rem
  padding: .2rem .25rem

  font-family: monospace
  color: #f8f5f0
  padding: .5rem 1.5rem
  background: #202122
  width: 100%
  //height: 25vh
  box-sizing: border-box
  overflow: auto

  font-size: 80%
    content: '> '
  + .console-line
    margin-top: .25rem
  font-size: .8rem
  margin-bottom: .5rem


                const area = document.querySelector('.console');

const appendLine = (text) => {
  const line = document.createElement('div');
  line.innerHTML = text;

const boxElm = document.querySelectorAll('.border-box')[0];

(function() {
const styles = window.getComputedStyle(boxElm);
const {marginTop, marginRight, marginBottom, marginLeft} = styles;
  console.log(marginTop, marginRight, marginBottom, marginLeft);

// clinetHeight / clientWidth 
const clientHeight = boxElm.clientHeight;

appendLine(`clientHeight: ${clientHeight}(px)`);

// offsetHeight / offsetWidth
const offsetHeight = boxElm.offsetHeight;
appendLine(`offsetHeight: ${offsetHeight}(px)`);

// getBoundingClientRect().height / getBoundingClientRect().width
const boundingClientRectHeight = boxElm.getBoundingClientRect().height;
appendLine(`getBoundingClientRect().height: ${boundingClientRectHeight} (px)`);

// get mergen
const boxElmStyle = window.getComputedStyle(boxElm);
const marginTop = boxElmStyle.marginTop;

appendLine(`document.defaultView.getComputedStyle(boxElm).marginTop ${marginTop}: (string)`);


appendLine(`Get Box size with mergen = Box height + border width * 2 + margin-top + margin-bottom`);
appendLine(`=> Element.getBoundingClientRect().height + document.defaultView.getComputedStyle(Element).marginTop + document.defaultView.getComputedStyle(Element).marginBottom`)
appendLine(boundingClientRectHeight + parseFloat(boxElmStyle.marginTop.replace('px', '')) + parseFloat(boxElmStyle.marginBottom));

const getBoundingSize = (element) => {
  const boundingClientRect = element.getBoundingClientRect();
  return {
    width: boundingClientRect.width,
    height: boundingClientRect.height,

const getElementsMargin = (element) => {
  const style = window.getComputedStyle(element);
  return {
    top: parseFloat(style.marginTop) || 0,
    right: parseFloat(style.marginRight) || 0,
    bottom: parseFloat(style.marginBottom) || 0,
    left: parseFloat(style.marginLeft) || 0,

const getOuterSize = (element) => {
  const margin = getElementsMargin(element);
  const size = getBoundingSize(element);
  return {
    width: size.width + margin.left + margin.right,
    height: size.height + + margin.bottom,

function setResult() {
  const resElm = document.querySelector('.result');
  resElm.innerHTML = '';
  const boxSize = getBoundingSize(boxElm);
  const outerBoxSize = getOuterSize(boxElm);
  const boxRect = boxElm.getClientRects()[0];
  const texts = [
    `clientWith / clientHeight: ${boxElm.clientWidth} / ${boxElm.clientHeight}`,
    `offsetWidth / offsetHeight: ${boxElm.offsetWidth} / ${boxElm.offsetHeight}`,
    `getClientRects: ${boxRect.width} / ${boxRect.height}`,
    `getBoundingClientRect: ${boxSize.width} / ${boxSize.height}`,
    `boxMargin: ${Object.entries(getElementsMargin(boxElm)).map(([key, val]) => `${key}: ${val}`).join(', ')}`,
    `outerWidth / outerHeight: ${outerBoxSize.width} / ${outerBoxSize.height}`,
  const flagment = document.createDocumentFragment();
  texts.forEach((str) => {
    const div = document.createElement('div');
    div.textContent = str;

let timer;

window.addEventListener('resize', function() {
  timer && window.clearTimeout(timer);
  timer = window.setTimeout(() => {
  }, 100);