将数组中的数字相乘并以文字和点表示法添加到对象

Question

Just wondering how to do this code in literal and dot notation

function multi(num){
  var obj = {};
  for(var i = 0; i < num.length; i++){
    obj[num[i]] = num[i] * 2;

  }
  return obj;  
}

If you use literal notation you cannot define the object like so obj = {num[i] : num[i]*2} same goes for dot notation obj.num[i] = num[i] * 2 will not work seeing as the key in literal and dot notation needs to be an actual string. Is there a way to define the key of an object as the current number and the value the current number multiplied by two of an object with literal or dot notation?

Answer 1

so not doable in any other notation besides bracket? – jharclerode

On a browser that supports Object.defineProperty (ECMA5) you also have this alternative, if you really must.

function multi(num) {
    var obj = {};
    for (var i = 0; i < num.length; i++) {
        Object.defineProperty(obj, num[i], {
            value: num[i] * 2,
            enumerable: true
        });
    }
    return obj;
}

var nums = [1, 2, 3, 4, 5, 6, 7, 8, 9];

console.log(multi(nums));

On jsFiddle