Get the unique values from two arrays and put them in another array [duplicate]

Answer 1

Something like this

var array1 = ['12','1','10','19','100'];
var array2 = ['12','10','19'];
var o = {};
for(var i in array1) {
    o[i] = 1;
}
for(var i in array2) {
    o[i] = 0;
}
var array3 = [];
for(var i in o) {
    if(o[i] == 1) {
        array3.push(i);
    }
}

Answer 2

var array3 = array1.concat(array2);

array3 = array3.sort(function(a, b) { return a > b; });
array3 = array3.filter(function(num, index) { return num !== array3[index + 1]; });

array3 will have only unique values

this also does the job in two loops which is pretty inexpensive, it should be noted that sort() and filter() are ECMA5 functions and not supported in older browsers, also i usually use a library like underscore so i don't have rewrite these functions for each project i work on, underscore has a .unique() method which obviously is less code and more clearly states the intention of the operation

Answer 3

With a bit of ES6 magic it can be fairly concise. Note that we need to check both ways around in case there are unique items in either array.

const arr1 = [1, 2, 3, 4, 5];
const arr2 = [1, 3, 8];

let unique1 = arr1.filter((o) => arr2.indexOf(o) === -1);
let unique2 = arr2.filter((o) => arr1.indexOf(o) === -1);

const unique = unique1.concat(unique2);

console.log(unique);
// >> [2, 4, 5, 8]

Answer 4

var array1 = ['12','1','10','19','100'];
var array2 = ['12','10','19'];


var newArr,temp,temp1;


    temp=array1.filter(function(el) 
              {
                return arr2.indexOf(el) == -1; 

              });

    temp1=array2.filter(function(el) 
              {
                return arr1.indexOf(el) == -1; 

              });

  newArr=temp.concat(temp1);


  return newArr;

}

Answer 5

Similar to above but will work with more than two arrays

var array1 = ['12','1','10','19','100'];
var array2 = ['12','10','19'];
var i = 0;
var hist = {};
var array3 = [];

buildhist(array1);
buildhist(array2);

for (i in hist) {
    if (hist[i] === 1) {
        array3.push(i);
    }
}

console.log(array3);

function buildhist(arr) {
    var i;
    for (i = arr.length - 1; i >= 0; i--) {
        if (hist[arr[i]] === undefined) {
            hist[arr[i]] = 0;
        }
        hist[arr[i]]++;
    }
}

Answer 6

var array3 = array1.filter(function(obj) { return array2.indexOf(obj) == -1; });

MDN on Array#filter: https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Array/filter

Includes a polyfill for older browsers.