/* property01.js
define propiedades de un objeto
*/
var o = {a:1, b:2, c:3, d: 4};
for (var i in o) {
console.log('o[' + i + ']: ' + o[i]);
console.log('o.' + i + ': ' + o.i);
}
/* salida
o[a]: 1
o.a: undefined
o[b]: 2
o.b: undefined
o[c]: 3
o.c: undefined
o[d]: 4
o.d: undefined
*/
question: because o.a, o.b, o.c and o.d give indefinite
You are wrong in your approach. You are not trying
o.a
otherwise
o.i
In your code
console.log('o.' + i + ': ' + o.i);
that is the difference between using [ ] and not using it:
o[i] - > Evaluate i and use that value to search within o .
o.i - > does not evaluate i ; It is taken literally.
You can easily check if you do
var o = {a:1, b:2, c:3, d: 4, i: '¡ Es verdad' };