Why JSON.parse hides the location of certain syntax errors in your code

JavaScript's JSON.parse provides character-position details for some syntax errors, such as trailing commas or bad escape sequences, but stays silent on location for inputs like NaN, undefined, or Python-style True values. This gap is most problematic when parsing large, hand-edited or pasted documents where spotting a rogue token by eye is impractical. One workaround involves binary-searching prefixes of the input string, repeatedly calling JSON.parse on slices to narrow down the fault, though this runs at O(n log n) complexity and adds parsing overhead. The approach also breaks across browser engines, since it relies on matching V8-specific error message text that does not appear in Safari's JavaScriptCore, which itself reports positional data for none of the tested error cases. The inconsistency means a fix validated entirely in Node.js can silently fail for Safari users, highlighting how cross-engine differences in error reporting remain an unresolved pain point.