Lodash
JavaScript
var data = [
{ rel: 'link1', href: 'url1', titi: 'toto'},
{ rel: 'link2', href: 'url2', titi: 'toto'},
{ rel: 'link3', href: 'url3', titi: 'toto'},
{ rel: 'link4', href: 'url4', titi: 'toto'},
];
var hashmap = _.reduce(data, function(hash, value) {
var key = value['rel'];
hash[key] = value['href'];
return hash;
}, {});
console.log(hashmap);