How Can I Access JavaScript Object Properties Dynamically?

Accessing JavaScript Object Properties Dynamically by Name

Consider an object with boolean properties:

var columns = {
  left: true,
  center: false,
  right: false
};

To retrieve a property value dynamically based on a provided string variable, such as "right," you can use either bracket or dot notation.

Bracket Notation:

var side = columns['right'];

This method allows referencing property names stored in variables or obtained dynamically.

Dot Notation:

var side = columns.right;

Dot notation is ideal when the property name is a known string constant.

Function for Dynamic Property Access

If a function is preferred:

function read_prop(obj, prop) {
  return obj[prop];
}

Nested Objects

Nested object properties can be accessed using multiple brackets or dot notation, e.g.:

var foo = { a: 1, b: 2, c: { x: 999, y: 998, z: 997 } };
var cx = foo['c']['x'];

Undefined Properties

If a property is undefined, referencing it will return undefined:

foo['c']['q'] === null; // false
foo['c']['q'] === false; // false
foo['c']['q'] === undefined; // true

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