'use strict'; | |
var toPosInt = require('../../number/to-pos-integer') | |
, value = require('../../object/valid-value') | |
, hasOwnProperty = Object.prototype.hasOwnProperty; | |
module.exports = function () { | |
var i, l; | |
if (!(l = toPosInt(value(this).length))) return null; | |
i = 0; | |
while (!hasOwnProperty.call(this, i)) { | |
if (++i === l) return null; | |
} | |
return i; | |
}; |