I have an array with objects
const nodes = [ { children: [1, 2, 3] }, { children: [1, 2, 3] } ];
I want a new array [ 1, 2, 3, 1, 2, 3 ].
I have tried
nodes.map(node => node.children);
but it gives me [ [ 1, 2, 3 ], [ 1, 2, 3 ] ].
I have tried
[].concat(nodes.map(node => node.children));
but it doesn't work since it is just concatenating [] with [ [ 1, 2, 3 ], [ 1, 2, 3 ] ] which is just [ [ 1, 2, 3 ], [ 1, 2, 3 ] ].
You could use Array#reduce
const nodes = [ { children: [1, 2, 3] }, { children: [1, 2, 3] } ],
result = nodes.reduce((r, node) => r.concat(node.children), []);
console.log(result);
console.log([... new Set(result)]); // for unique values.as-console-wrapper { max-height: 100% !important; top: 0; }
.filter((item, pos, self) => self.indexOf(item) == pos). Does it make sense to do this inside the reduce instead of afterwards with chaining?
Set for unique values.Array.from(new Set(result))?You can do this with Array#reduce
const nodes = [ { children: [1, 2, 3] }, { children: [1, 2, 3] } ];
var result = nodes.reduce(function(r, o) {
r = r.concat(o.children);
return r;
}, []);
console.log(result)Another way to do this using Array#forEach:
const nodes = [ { children: [1, 2, 3] }, { children: [1, 2, 3] } ]
final = []
nodes.forEach(x => final = final.concat(x.children))
console.log(final)Another shorter way is (a little modification to what OP was trying to do):
const nodes = [ { children: [1, 2, 3] }, { children: [1, 2, 3] } ];
var result = [].concat.apply([], nodes.map(x => x.children))
console.log(result);