How Can I Add New Key-Value Pairs to a JavaScript Object?

Adding New Key-Value Pairs to JavaScript Objects

In JavaScript, objects serve as containers for storing key-value pairs. To enhance these objects, you may need to add new fields.

Method 1: Dot Notation (Key Known)

var obj = {
    key1: value1,
    key2: value2
};
obj.key3 = "value3";

Method 2: Square Bracket Notation (Dynamic Key)

var obj = {
    key1: value1,
    key2: value2
};
obj["key3"] = "value3";

Distinction

Dot notation is preferable when the key name is known upfront. Square bracket notation provides flexibility when determining the key name dynamically.

Array Construction

Array Literal Notation:

var arr = [];

Array Constructor Notation:

var arr = new Array();

Both methods create an empty array in JavaScript.

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