How to get Unique Id?

[hitesh-dhamshaniya]

Actually it is not an issue, but I din't find another way to ask this question. so I choose it.

var recommendations = myFirebase.child("recommendations");

// Push our first recommendation to the end of the list and assign it a
// unique ID automatically.
recommendations.push({
"id":"uniqueID" // how can I get id
"title": "The danger of a single story",
"presenter": "Chimamanda Ngozi Adichie",
"link": "https://www.ted.com/talks/chimamanda_adichie_the_danger_of_a_single_story"
});