[spokodev]

Problem

Integer-valued numbers with magnitude >= 1e21 are silently corrupted on a build -> parse round-trip.

plist.parse(plist.build(1e21))    // => 1      (expected 1e21)
plist.parse(plist.build(-1e21))   // => -1     (expected -1e21)
plist.parse(plist.build(1.23e30)) // => 1      (expected 1.23e30)

No error is thrown, so callers have no signal that 21+ orders of magnitude were lost.

Cause

build classifies any integer-valued number as <integer> and serializes it with Number.prototype.toString():

const tag_type = next % 1 === 0 ? 'integer' : 'real';
next_child.ele(tag_type).txt(next.toString());

For |x| >= 1e21, toString() returns exponential notation, e.g. (1e21).toString() === "1e+21", producing <integer>1e+21</integer>. On parse, the <integer> branch does parseInt(value, 10), which stops at the e and returns 1.

The boundary is exactly 1e21: values below it (including 1e20 and 562341325190349060000) stringify in plain decimal and round-trip fine. The binary path (buildBinary/parseBinary) round-trips 1e21 correctly, so this is an XML-text serialization defect, not a representational limit.

Apple's PLIST DTD defines <integer> and <real> as the two numeric element types; a value that cannot be expressed as a plain-decimal integer string belongs in <real>.

Fix

Classify a number as <integer> only when it is a true integer below the exponential threshold; otherwise emit <real>:

const tag_type =
  Number.isInteger(next) && Math.abs(next) < 1e21 ? 'integer' : 'real';

The <real> parse branch already uses parseFloat, which recovers 1e+21 exactly. Values below 1e21 keep the existing <integer> output, so there is no behavior change for the common case.

Test

Added a round-trip test under parse() > integer. It fails on master (expected 1 to be 1e+21) and passes with the fix. Full suite: 113 passing.

Note

src/build.browser.ts (line ~76) has the same classification logic and the same defect. I scoped this PR to the Node path that the repro exercises; let me know if you want the browser build fixed in this PR or a follow-up.

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[changeset-bot]

🦋 Changeset detected

Latest commit: 01f9ffb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
plist	Patch

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