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Fall back to HTML parser if XML parser rejects #31

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Merged
GarboMuffin merged 1 commit into from
Jul 12, 2026
Merged

Fall back to HTML parser if XML parser rejects #31

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15 changes: 13 additions & 2 deletions core/xml.js
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Original file line number Diff line number Diff line change
Expand Up @@ -388,10 +388,21 @@ Blockly.Xml.domToPrettyText = function(dom) {
Blockly.Xml.textToDom = function(text) {
var oParser = new DOMParser();
var dom = oParser.parseFromString(text, 'text/xml');
// The DOM should have one and only one top-level node, an XML tag.
// The DOM should have one and only one top-level node, an XML tag, and no
// parse error (some invalid characters cause document to be truncated and
// a <parsererror> is generated)
if (!dom || !dom.firstChild ||
dom.firstChild.nodeName.toLowerCase() != 'xml' ||
dom.firstChild !== dom.lastChild) {
dom.firstChild !== dom.lastChild ||
dom.getElementsByTagName('parsererror').length) {
// Matching Scratch, fall back to the lenient HTML parser when the text is
// not valid XML. Some "interesting" projects put control characters in
// inputs, which are illegal in XML 1.0 but tolerated by the HTML parser.
var htmlDom = oParser.parseFromString(text, 'text/html');
if (htmlDom && htmlDom.body.firstChild &&
htmlDom.body.firstChild.nodeName.toLowerCase() == 'xml') {
return htmlDom.body.firstChild;
}
// Whatever we got back from the parser is not XML.
goog.asserts.fail('Blockly.Xml.textToDom did not obtain a valid XML tree.');
}
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