My array is not pushing at last position var testString = ['first', 'second', 'third']; 
var concatString = ['fourth']; 
concatString.push(testString); 
console.log(concatString);
var testString = ['first', 'second', 'third']; var concatString = ['fourth']; testString.concat(concatString); console.log(testString);
var hege = ["Cecilie", "Lone"];
var stale = ["Emil", "Tobias", "Linus"];
var children = hege.concat(stale);
Output:
Cecilie,Lone,Emil,Tobias,Linus