graphData.haveItem.js

graphData.haveItem.js

const graphData = {
  nodes: [
  {id:1, name:'Facu'},
  {id:2, name:'Cari'},
  {id:3, name:'Fran'},
  {id:4, name:'Martina'}
 ],
  links: [
    {source:1, target:2},
    {source:3, target:2},
    {source:3, target:1},
    {source:4, target:1},
  ]
}

const haveLinks = (node, links) => Boolean(links.filter(link=>link.source===node.id).length || links.filter(link=>link.target===node.id).length)

const unlinkedNodes = ({nodes, links}) => !nodes.every(node => haveLinks(node, links))

console.log(unlinkedNodes(graphData)) // -> false
graphData.links.pop()
console.log(unlinkedNodes(graphData)) // -> true