Brackets in Functions Javascript

Question

I am having trouble understanding the usage of brackets in \"for\" loops and \"if\" statements in Javascript. I have seen syntax in Javascript where there is brackets and where

Answer 1

Bracket allow you to add more statement into one block. if I modify bit to show result

function range(upto) {
  var result = [];
  for (var i = 0; i <= upto; i++) {
    result[i] = i;
    result[i] = result[i]*2
  }
    return result;

}
console.log(range(15));

Result will be

[2,4,6,8,10,12,14,16,18,20,22,24,26,28,30]

however, without bracket,

function range(upto) {
      var result = [];
      for (var i = 0; i <= upto; i++) 
        result[i] = i;
        result[i] = result[i]*2

        return result;

    }
    console.log(range(15));

result will be like this

[1,2,3,4,5,6,7,8,9,10,11,12,13,14,30]

*being rookie programmer, I think it probably will fail due to undeclared variable