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Surface style recalculation work in the page-x-ray diff #168

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Merged
soulgalore merged 1 commit into from
May 12, 2026
Merged

Surface style recalculation work in the page-x-ray diff #168

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29 changes: 29 additions & 0 deletions public/js/compare/templates.js
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Original file line number Diff line number Diff line change
Expand Up @@ -232,6 +232,35 @@ function pageXrayTemplate(d) {
'<td>' + p1.renderBlocking.in_body_parser_blocking + '</td>' +
'<td>' + p2.renderBlocking.in_body_parser_blocking + '</td>' +
diffCell(p1.renderBlocking.in_body_parser_blocking, p2.renderBlocking.in_body_parser_blocking) + '</tr>';

// Style recalculation before FCP / LCP. Sitespeed.io / browsertime
// captures how many elements the browser re-styled and how long it
// took on its way to each paint milestone — both are "lower is
// better", so the existing diff colouring applies. Guarded so a
// plain Chrome HAR (no recalculateStyle) doesn't render four empty
// rows.
const rs1 = p1.renderBlocking.recalculateStyle;
const rs2 = p2.renderBlocking.recalculateStyle;
if (rs1 && rs2) {
function recalcRow(label, a, b, formatter) {
return '<tr><td class="tabletext">' + h(label) + '</td>' +
'<td>' + (formatter ? formatter(a) : a) + '</td>' +
'<td>' + (formatter ? formatter(b) : b) + '</td>' +
diffCell(a, b, formatter) + '</tr>';
}
if (rs1.beforeFCP && rs2.beforeFCP) {
html += recalcRow('Style recalc elements (before FCP)',
rs1.beforeFCP.elements, rs2.beforeFCP.elements);
html += recalcRow('Style recalc duration (before FCP)',
rs1.beforeFCP.durationInMillis, rs2.beforeFCP.durationInMillis, formatTime);
}
if (rs1.beforeLCP && rs2.beforeLCP) {
html += recalcRow('Style recalc elements (before LCP)',
rs1.beforeLCP.elements, rs2.beforeLCP.elements);
html += recalcRow('Style recalc duration (before LCP)',
rs1.beforeLCP.durationInMillis, rs2.beforeLCP.durationInMillis, formatTime);
}
}
}

if (p1.visualMetrics) {
Expand Down