Types in JavaScript

In JavaScript, there are several types of data that you can use in your programs.

  • Number: A numeric value. JavaScript has only one type of number, which can be an integer or a floating-point value.

Example:

const x = 10;
const y = 3.14;
  • String: A sequence of characters. Strings can be enclosed in single or double quotes.

Example:

const str = "hello";
const str2 = 'world';
  • Boolean: A value that represents true or false.

Example:

const flag = true;
const flag2 = false;
  • Null: A value that represents the absence of a value.

Example:

const x = null;
  • Undefined: A value that represents the absence of a value that has not been assigned.

Example:

const x;
console.log(x);  // prints undefined
  • Object: A collection of key-value pairs.

Example:

const obj = {
  name: "John",
  age: 30
};

In JavaScript, the type of a value is determined at runtime, and the same value can have different types at different points in the program.

JavaScript has a built-in function called typeof that returns a string that represents the type of a value.

Example:

console.log(typeof 10);     // prints "number"
console.log(typeof "hello"); // prints "string"
console.log(typeof true);    // prints "boolean"
console.log(typeof {});      // prints "object"

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