delete uninitialized variable globalX: false
globalX : undefined
delete explicitVar       : false
value  explicitVar       : 10
delete implicitVar       : true
value  implicitVar       : Exception
delete explicitVarInEval : true
value  explicitVarInEval : Exception
delete implicitVarInEval : true
value  implicitVarInEval : Exception
a[1] = 200
delete a[1] : true
a[1] = undefined
a[2] = 100
delete a[2] : true
a[2] = 100
o.x = 1
delete o.x : true
o.x = undefined
delete o.x (again): true
o.z = undefined
delete o.z (non existing property): true
o.z = undefined