If object does not have key, add it.
Acest script nu ar trebui instalat direct. Aceasta este o bibliotecă pentru alte scripturi care este inclusă prin directiva meta a // @require https://update.greasyfork.org/scripts/427473/937466/object_setDefault.js
Added method setDefault to object prototype.
function setDefault (key, value)
If object does not have key, add it with value value
key (string, required)
key to check
value (any, optional, default = undefined)
value for key if it's not present