JSFiddle - React, Tailwind, and code Playground

by auzwang

JavaScript

var nodes = [
    { 
        name: 'java',
        followers: [
            { name: 'ABC', email: 'abc@abc.com' },
            { name: 'IJK', email: 'ijk@ijk.com' },
            { name: 'LMN', email: 'lmn@lmn.com' }
        ]
    },
    { 
        name: 'javascript',
        followers: [
            { name: 'ABC', email: 'abc@abc.com' },
            { name: 'IJK', email: 'ijk@ijk.com' },
            { name: 'XYZ', email: 'xyz@xyz.com' }
        ]
    },
    { 
        name: 'programming',
        followers: [
            { name: 'XYZ', email: 'abc@abc.com' },
            { name: 'IJK', email: 'ijk@ijk.com' },
            { name: 'PQR' }
        ]
    }
];

const emails = nodes.reduce((set, node) => {
	return node.followers.reduce((set, follower) => {
  	follower.email && set.add(follower.email);
    return set;
  }, set);
}, new Set());

console.log([...emails]);