Common data types in js

Common data types in JavaScript are divided into basic types (Number, String, Boolean, Null, Undefined) and complex types (Array, Object, Date, RegExp, Error). Use the typeof operator to determine the type of data, such as console.log(typeof 42) output "number".

Common data types in JavaScript

Data types in JavaScript refer to the storage and processing of different types Classification of variables in the data. The following are several common data types in JavaScript:

1. Basic data types

• Number: Numeric value.
• String: String.
• Boolean: Boolean value (true or false).
• Null: Null value.
• Undefined: The value of the variable is not declared.

2. Complex data type

• Array: A set of elements arranged in sequence.
• Object: A set of key-value pairs.
• Date: Date and time.
• RegExp: Regular expression.
• Error: Error object.

3. Special data types

• Symbol: Unique identifier.
• BigInt: An integer, but larger than Number.

How to determine the type of data

You can use the typeof operator to determine the data type of a variable. For example:

<code class="js">console.log(typeof 42); // "number"
console.log(typeof "hello world"); // "string"
console.log(typeof true); // "boolean"
console.log(typeof null); // "object"
console.log(typeof undefined); // "undefined"</code>

It should be noted that although null is a special value, it is treated as an object in JavaScript.

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