I have below array format and i want to make union of it using lodash or normal js.
var testArray = [[1,2,3,4,5,6,7,8],[1,2,3,4,5,10,7,8],[1,2,3,6,7,8],[9],[3,4,5]]
I want to make union of all these into one and output should be below array.
testArray = [1,2,3,4,5,6,7,8,9,10]
You could combine flattenDeep with _.union. If needed apply sorting
var testArray = [[1,2,3,4,5,6,7,8],[1,2,3,4,5,10,7,8],[1,2,3,6,7,8],[9],[3,4,5]],
result = _.chain(testArray)
.flattenDeep()
.union();
console.log(result);<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.15.0/lodash.min.js"></script>
[1,2,3,4,5,6,7,8,9,10] .but your answer like [1,2,3,4,5,6,7,8,10,9] .why last two number was swap? is right or wrong?
Apply _.union() to the parent array:
var testArray = [[1,2,3,4,5,6,7,8],[1,2,3,4,5,10,7,8],[1,2,3,6,7,8],[9],[3,4,5]];
var result = _.union.apply(_, testArray);
console.log(result);<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.2/lodash.min.js"></script>Or use array spread if ES6 is supported:
const testArray = [[1,2,3,4,5,6,7,8],[1,2,3,4,5,10,7,8],[1,2,3,6,7,8],[9],[3,4,5]];
const result = _.union(...testArray);
console.log(result);<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.2/lodash.min.js"></script>With ES6 you can do this using spread syntax ... and Set
var testArray = [[1,2,3,4,5,6,7,8],[1,2,3,4,5,10,7,8],[1,2,3,6,7,8],[9],[3,4,5]]
var result = [...new Set([].concat(...testArray))];
console.log(result)You can just call _.union.apply(null, arrays). It is documented here:
https://lodash.com/docs/#union
> var testArray = [[1,2,3,4,5,6,7,8],[1,2,3,4,5,10,7,8],[1,2,3,6,7,8],[9],[3,4,5]]
> lodash.union.apply(null, testArray)
[ 1, 2, 3, 4, 5, 6, 7, 8, 10, 9 ]
The apply trick is to transform your array of array in to function call arguments. If you need it sorted as well, you can just tuck .sort() at the end of it.
In just ES5 if you need that:
var flattened = Object.keys(testArray.reduce(function(acc, cur) {
cur.forEach(function(v) {acc[v] = true;});
return acc;
}, {})).sort(function(a, b) {return a - b;});
