unique.js

$ cat unique.js
#!/usr/bin/env node

talks = [
  { 'id' : 1, name : 'foo' },
  { 'id' : 2, name : 'foo' },
  { 'id' : 3, name : 'bar1' },
  { 'id' : 3, name : 'bar2' },
  { 'id' : 4, name : 'bar3' },
  { 'id' : 5, name : 'bar4' }
]

var say = (e) => console.log(e)

function unique_by(attr,list) {
    var seen = {}
    return list.filter( ( {[attr] : id}, i) => {
            seen[id] = seen[id] || 0
            return ! seen[id]++
    } )
}

say( unique_by('id', talks) )
say( unique_by('name', talks) )
$ ./unique.js
[ { id: 1, name: 'foo' },
  { id: 2, name: 'foo' },
  { id: 3, name: 'bar1' },
  { id: 4, name: 'bar3' },
  { id: 5, name: 'bar4' } ]
[ { id: 1, name: 'foo' },
  { id: 3, name: 'bar1' },
  { id: 3, name: 'bar2' },
  { id: 4, name: 'bar3' },
  { id: 5, name: 'bar4' } ]
$