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// https://stackoverflow.com/questions/6209161/extract-the-current-dom-and-print-it-as-a-string-with-styles-intact
//
// Mapping between tag names and css default values lookup tables. This allows to exclude default values in the result.
const defaultStylesByTagName = {};
// Styles inherited from style sheets will not be rendered for elements with these tag names
const noStyleTags = {
BASE: true,
HEAD: true,
HTML: true,
META: true,
NOFRAME: true,
NOSCRIPT: true,
PARAM: true,
SCRIPT: true,
STYLE: true,
TITLE: true
};
// This list determines which css default values lookup tables are precomputed at load time
// Lookup tables for other tag names will be automatically built at runtime if needed
const tagNames = [
"A",
"ABBR",
"ADDRESS",
"AREA",
"ARTICLE",
"ASIDE",
"AUDIO",
"B",
"BASE",
"BDI",
"BDO",
"BLOCKQUOTE",
"BODY",
"BR",
"BUTTON",
"CANVAS",
"CAPTION",
"CENTER",
"CITE",
"CODE",
"COL",
"COLGROUP",
"COMMAND",
"DATALIST",
"DD",
"DEL",
"DETAILS",
"DFN",
"DIV",
"DL",
"DT",
"EM",
"EMBED",
"FIELDSET",
"FIGCAPTION",
"FIGURE",
"FONT",
"FOOTER",
"FORM",
"H1",
"H2",
"H3",
"H4",
"H5",
"H6",
"HEAD",
"HEADER",
"HGROUP",
"HR",
"HTML",
"I",
"IFRAME",
"IMG",
"INPUT",
"INS",
"KBD",
"KEYGEN",
"LABEL",
"LEGEND",
"LI",
"LINK",
"MAP",
"MARK",
"MATH",
"MENU",
"META",
"METER",
"NAV",
"NOBR",
"NOSCRIPT",
"OBJECT",
"OL",
"OPTION",
"OPTGROUP",
"OUTPUT",
"P",
"PARAM",
"PRE",
"PROGRESS",
"Q",
"RP",
"RT",
"RUBY",
"S",
"SAMP",
"SCRIPT",
"SECTION",
"SELECT",
"SMALL",
"SOURCE",
"SPAN",
"STRONG",
"STYLE",
"SUB",
"SUMMARY",
"SUP",
"SVG",
"TABLE",
"TBODY",
"TD",
"TEXTAREA",
"TFOOT",
"TH",
"THEAD",
"TIME",
"TITLE",
"TR",
"TRACK",
"U",
"UL",
"VAR",
"VIDEO",
"WBR"
];
function computeDefaultStyleByTagName(tagName) {
const defaultStyle = {};
const element = document.body.appendChild(document.createElement(tagName));
const computedStyle = getComputedStyle(element);
for (let i = 0; i < computedStyle.length; i++) {
defaultStyle[computedStyle[i]] = computedStyle[computedStyle[i]];
}
document.body.removeChild(element);
return defaultStyle;
}
function getDefaultStyleByTagName(tagName) {
tagName = tagName.toUpperCase();
if (!defaultStylesByTagName[tagName]) {
defaultStylesByTagName[tagName] = computeDefaultStyleByTagName(tagName);
}
return defaultStylesByTagName[tagName];
}
export default function serializeElement(el) {
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if (Object.keys(defaultStylesByTagName).length === 0) {
// Precompute the lookup tables.
for (let i = 0; i < tagNames.length; i++) {
if (!noStyleTags[tagNames[i]]) {
defaultStylesByTagName[tagNames[i]] = computeDefaultStyleByTagName(tagNames[i]);
}
}
}
if (el.nodeType !== Node.ELEMENT_NODE) {
throw new TypeError();
}
const cssTexts = [];
const elements = el.querySelectorAll("*");
for (let i = 0; i < elements.length; i++) {
const e = elements[i];
if (!noStyleTags[e.tagName]) {
const computedStyle = getComputedStyle(e);
const defaultStyle = getDefaultStyleByTagName(e.tagName);
cssTexts[i] = e.style.cssText;
for (let ii = 0; ii < computedStyle.length; ii++) {
const cssPropName = computedStyle[ii];
if (computedStyle[cssPropName] !== defaultStyle[cssPropName]) {
e.style[cssPropName] = computedStyle[cssPropName];
}
}
}
}
const result = el.outerHTML;
for (let i = 0; i < elements.length; i++) {
elements[i].style.cssText = cssTexts[i];
}
return result;
}