display object properties using for/in loop javascript

Question

below is a simple samlple, i wanna display the object properties using for/in loop

var Object = { x:1, y:2, z:3 };
for (property in Object) {
  console.log(Object.property);
};

it shows undefined.

but if using console.log(Object[property]); it works, and shows 1 2 3

why i cannot use Object.property to display in for/in loop?

First, you would use `Object[property]`. Second, **don't** use "Object" as the variable's name - it's the object constructor, and may or may not mess up other things...**especially** if this code is in the global scope — Ian, Jun 11 '13 at 16:52

Halcyon · Accepted Answer · 2013-06-11T16:58:16.430

This has to do with notation and syntax

Object.property will give you undefined because you're accessing the property with the name property.

If you have this object:

var o = {
    property: "value",
    value: "foo"
};

o.property; // "value"
o["property"]; // "value" (equivalent)
o.value; // "foo"
o["value"]; // "foo" (equivalent)
o[o.property]; // "foo" no other notation possible

So in:

var Object = { x:1, y:2, z:3 };
for (property in Object) {
  console.log(Object.property);
};

The value of property is "x", "y" and then "z". But Object.property is equivalent to Object["property"]. Whereas Object[property] gives you Object["x"] etc.

thanks so much @Frits van Campen – Will Jun 11 '13 at 17:11 — Will, Jun 11 '13 at 17:11

display object properties using for/in loop javascript

1 Answers1