fix: O(n²) jPath degradation when tag names contain dots

[dollebrolle]

Purpose / Goal

Fixes #793

The jPath variable in OrderedObjParser.js uses . as a separator to track tag hierarchy (e.g., root.parent.child). When closing tags, lastIndexOf(".") is used to pop back one level. However, when tag names themselves contain dots (e.g., <applink.ios_url>), lastIndexOf(".") finds the dot within the tag name instead of the hierarchy separator, causing incorrect truncation.

This leaves residue in the jPath string that accumulates with every dotted tag processed, resulting in O(n²) performance degradation.

Changes

Replaced all 6 lastIndexOf(".")-based jPath truncations with a popTagFromJPath(jPath, tagName) helper that uses the known tag name length to compute the exact substring position. Since jPath is always built by appending "." + tagName, we can reverse it precisely without searching for dots.

Additionally, lastTagName (used for unpaired tag detection) is now read from currentNode.tagname instead of being parsed from jPath via lastIndexOf(".").

Benchmark

Parser              | Before fix | After fix
fxp v3 (baseline)   | 75,283     | 75,802
fxp                  | 49,306     | 52,690
fxp - preserve order | 53,841     | 56,949
xmlbuilder2          | 18,397     | 18,469
xml2js               | 22,083     | 21,319

No performance regression for standard XML parsing.

Type

• Bug Fix
• Refactoring / Technology upgrade
• New Feature

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[amitguptagwl]

Thanks for your changes. I'm planning to handle it differently. Working on this. will update in few days