javascript - Syntax error when accessing property by variable? -

i have json variable stored in $("#budget").data('allocations')

i can access it's data this:

id = "5"; alert( $("#budget").data('allocations')[id].amount );

but need access this:

var id = "5"; var field = "amount";  alert( $("#budget").data('allocations')[id].[field] );

using variable in property name causes fail.

missing name after . operator (referring [field])

basically, .xxx can replaced ["xxx"] , there no limit in combining. use same logic used id:

$("#budget").data('allocations')[id][field]

whenever key in variable, replace .key [variable]. so, obj.key1.key2 becomes obj[variable1][variable2] same logic.

OSX