MongoDB iteration on aggregate - mongodb

Question

I have a collection :
{
"value" : "20",
"type" : "square",
"name" : "form1"
},
{
"value" : "24",
"type" : "circle",
"name" : "form2"
},
{
"value" : "12",
"type" : "square",
"name" : "form3"
}
This aggregation :
let searchTerm = "form2"
db.myCollec.aggregate([
{ "$facet": {
"data": [
{ "$match": { "name": searchTerm }},
{ "$project": { "name": 1, "type": 1, "_id": 0 }}
]
}},
{ "$project": {
"name": {
"$ifNull": [{ "$arrayElemAt": ["$data.name", 0] }, searchTerm ]
},
"type": {
"$ifNull": [{ "$arrayElemAt": ["$data.type", 0] }, null]
}
}}
])
give this result :
{ "name" : "form2", "type" : "circle" }
and if i'm looking for a non existing "form4" :
{ "name" : "form4", "type" : null }
Now I want to do it for a lot of values so I try to put them in an array then loop on this array. According to the asynchronous property of javascript I try this code :
tab = [ "form2", "form4" ]
for( var i =0; i<(tab.length);i++) { (function (i) {
searchTerm = tab[i]
db.myCollec.aggregate([
{ "$facet": {
"data": [
{ "$match": { "name": searchTerm }},
{ "$project": { "name": 1, "type": 1, "_id": 0 }}
]
}},
{ "$project": {
"name": {
"$ifNull": [{ "$arrayElemAt": ["$data.name", 0] }, searchTerm ]
},
"type": {
"$ifNull": [{ "$arrayElemAt": ["$data.type", 0] }, null]
}
}}
])
}) (i) }
There is no result...
If I add a print(searchTerm) the values are well printed but no result for the aggregation.
Thanx for your help.