I want to push values of 3 arrays in a new array without repeating the same values
var a = ["1", "2", "3"]; var b = ["3", "4", "5"]; var c = ["4", "5", "6"]; var d = []; function newArray(x, y, z) { for(var i = 0; i < d.length; i++) { if(d.length == -1) { d[i].push(a[i]) } } for(var i = 0; i < d.length; i++) { if(d.length == -1) { d[i].push(y[i]) } } for(var i = 0; i < d.length; i++) { if(d.length == -1) { d[i].push(z[i]) } } } newArray(a, b, c); d = ["1", "2", "3", "4", "5", "6"]; You can use concat() and Set together as below,
var a = ["1","2","3"]; var b = ["3","4","5"]; var c = ["4","5","6"]; var d = a.concat(b).concat(c); var set = new Set(d); d = Array.from(set); console.log(d);If your goal is to remove duplicates, you can use a set,
var arr = [1, 2, 3, 4, 5, 5, 6, 6, 6, 7] var mySet = new Set(arr) var filteredArray = Array.from(mySet) console.log(filteredArray.sort()) // [1,2,3,4,5,6,7]
concat for appending arr2 to arr1: arr1 = Array.from(new Set(arr1.concat(arr2)));You could save yourself some time and effort with the very useful utility library Lodash.
The function you're looking for is Union
As stated by Lodash:
Creates an array of unique values, in order, from all given arrays using SameValueZero for equality comparisons.
Example
_.union([2], [1, 2]); // => [2, 1] 
var a = ["1","2","3"] , b = ["3","4","5"] , c = ["4","5","6"] , d = []; function newArray(x,y,z) { x.concat(y,z).forEach(item =>{ if (d.indexOf(item) == -1) d.push(item); }); return d; } console.log(newArray(a,b,c));
var a = ["1", "2", "3"]; var b = ["3", "4", "5"]; var c = ["4", "5", "6"]; var d = []; var hash = []; AddToHash(a); AddToHash(b); AddToHash(c); function AddToHash(arr) { for (var i = 0; i < arr.length; i++) { if (!hash[arr[i]]) { hash[arr[i]] = 1; } else hash[arr[i]] += 1; } } for (var i = 0; i < hash.length; i++) { d.push(i); } console.log(d);Hope this helps
Here is another version:
var d = b.concat(c); d.forEach(function(el) { if (a.indexOf(el) === -1) { a.push(el) } }) ES6 version:
let d = b.concat(c); d.forEach(el => { if (a.indexOf(el) === -1) { a.push(el) } }) 
d = [...new Set([...a, ...b, ...c])];