pub fn array_index(k: &str) -> Option<u32>Expand description
If k is an array-index property key, return its numeric value. Per
ECMAScript, a String property key P is an array index iff
ToString(ToUint32(P)) === P and ToUint32(P) !== 2^32 - 1 — i.e. a
canonical decimal (no leading zeros, no sign) in the range 0..=2^32-2.