Why is xml-to-json function returning exponential notation?

Question

All of my XSLT is working when using the xml-to-json() function except for this part,

<number key="send_at">
    <xsl:text>1615842000</xsl:text>
</number>

which returns

"send_at":1.615842E9

when I intend to get this result:

"send_at":1615842000

Answer 1

XPath 3.1 ^_(current)

Converting numbers to exponential notation is correct according to the spec (XPath and XQuery Functions and Operators 3.1):

17.5.4 fn:xml-to-json

Rules

Nodes in the input tree are handled by applying the following rules, recursively.

4. An element $E named number results in the output of the string result of xs:string(xs:double(fn:string($E)))

The fn:xml-to-json function does allow an $options argument, which provides a means for implementation-dependent extensions. Saxon 10.5 already leverages this mechanism to support passing through the value, without regard to JSON validity: ¹

map{'number-formatter':function($x){$x}}

XPath 4 ^_(upcoming)

A formatter is an officially supported option to fn:xml-to-json planned for XPath 4: ²

number-formatter: Determines how numeric values should be formatted.

• Type: (function(xs:string) as xs:string)?
• Default: ()

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_{¹ Thanks to Michael Kay for noting this mechanism (and foreseeing its need (and already implementing it in Saxon 10.5)).
² Thanks to Martin Honnen for noting this XPath 4 update.}