lodash merge two arrays of objects by key code example

Example 1: how to merge 2 object array by the same key with lodash

Lodash
var a = [
  { userId:"p1", item:1},
  { userId:"p2", item:2},
  { userId:"p3", item:4}
];

var b = [
  { userId:"p1", profile:1},
  { userId:"p2", profile:2},
  { userId:"p4", profile:4}
];
var merged = _.merge(_.keyBy(a, 'userId'), _.keyBy(b, 'userId'));
var values = _.values(merged);
console.log(values);
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Example 2: lodash merge array of objects without duplicates

var c = _.map(a, function(obj) {
    return _.assign(obj, _.find(b, {parentId: obj.aId}));
})