Use of if-else in JavaScript ES6

Question

I am learning ES6 and following is my ES5 code which is running fine -

var myArr = [34,45,67,34,2,67,1,5,90];
var evenArr = [];
var oddArr = [];

myArr.map(function(x){
  if(x%2==0) evenArr.push(x);
  else oddArr.push(x);
});

Now if I am converting this to ES6 I am getting errors of Unexpected token near if, let me know what I am doing wrong here -

My ES6 code -

var myArr = [34,45,67,34,2,67,1,5,90];
var evenArr = [];
var oddArr = [];
myArr.map( x => if(x%2==0) evenArr.push(x) else oddArr.push(x) )

Answer 1

That's because the arrow functions accept expressions while you're passing a statement.

Your code is misleading: Array.prototype.map implies you would use the result somehow, while you are not.

If you wanted to improve the semantics of your code you would use Array.prototype.forEach that is designed specifically to iterate over an array and not return anything:

var myArr = [34,45,67,34,2,67,1,5,90];
var evenArr = [];
var oddArr = [];
myArr.forEach(x => {
    if (x % 2 === 0) {
        evenArr.push(x);
    } else {
        oddArr.push(x);
    }
});

References:

• Array.prototype.forEach()
• Arrow functions