Pop part of array in node.js

Question

I have the array:

[ { x: 0,
    y: 1,
    z: 2,
    w: 3 },
  { x: 1,
    y: 2',
    z: 3 } ]

How can I pop "w"? I need the result:

[ { x: 0,
    y: 1,
    z: 2 },
  { x: 1,
    y: 2',
    z: 3 } ]

Answer 1

w isn't in an array, it's in an object (which is in an array, as the first entry). You can read its value like this:

var w = theArray[0].w;

you can remove it from the object like this:

delete theArray[0].w;

There's no built-in single operation that reads the value and deletes it, like Array#pop or Array#splice do.

---

Note: It usually doesn't matter, but deleting properties from objects on modern JavaScript engines usually has a negative impact on the performance of reading properties from the object afterward. This is because modern engines create on-the-fly classes for objects (and then subclass them when you add more properties), but deleting a property causes the object to fall back to the much-less-optimized "dictionary" (e.g., map) mode. Of course, this varies by JavaScript engine.