JavaScript array objects to one-column csv string

Question

Is there a way to convert my array into a string using only one of the properties of each object?

Given:

[{f1:'v1', f2:'v21'}, {f1:'v2', f2:'v22'}, {f1:'v3', f2:'v23'}]

Desired

'v21,v22,v23'

• jonatjano: how do you chose which property is the correct one ?
• Rod: oops, had an error in JSON, want to use f2 property

Answer 1

let input = [{
 f1: 'v1',
 f2: 'v21'
}, {
 f1: 'v2',
 f2: 'v22'
}, {
 f1: 'v3',
 f2: 'v23'
}];
let output = input.map((item) => item.f2).join(',');
console.log(output);

• Jackson: You need to put the values of f1, f2 etc in quotes
• jonatjano: wouldn't it be better with reduce ?
• Petr Broz: That's probably a matter of preference. I think the combination of map and join is reasonably clean.
• Tyler: The only thing to be careful of with this, IE doesn't support lambda's(=>) or let's, so if this is running on the client and you need to support IE, you may need to re-write this with a normal function and var's.

Answer 2

Using reduce()

var arr = [{"f1":"v1","f2":"v21"},{"f1":"v2","f2":"v22"},{"f1":"v3","f2":"v23"}];
var res = arr.reduce((a, e)=>{a.push(e.f2); return a },[]).toString()
console.log(res)