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DataTypes & Conversion in JavaScript

Checking Data Types and Casting

Checking Data Types

To check the data type of a certain variable we use the typeof method.

Example:

// Different javascript data types
// Let's declare different data types

let firstName = "shaikhmd"; // string
let lastName = "shaikh"; // string
let country = "IN"; // string
let city = "Mum"; // string
let age = 250; // number, it is not my real age, do not worry about it
let job; // undefined, because a value was not assigned

console.log(typeof "shaikhmd"); // string
console.log(typeof firstName); // string
console.log(typeof 10); // number
console.log(typeof 3.14); // number
console.log(typeof true); // boolean
console.log(typeof false); // boolean
console.log(typeof NaN); // number
console.log(typeof job); // undefined
console.log(typeof undefined); // undefined
console.log(typeof null); // object
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Changing Data Type (Casting)

  • Casting: Converting one data type to another data type. We use parseInt(), parseFloat(), Number(), + sign, str() When we do arithmetic operations string numbers should be first converted to integer or float if not it returns an error.

String to Int

We can convert string number to a number. Any number inside a quote is a string number. An example of a string number: '10', '5', etc.
We can convert string to number using the following methods:

  • parseInt()
  • Number()
  • Plus sign(+)
let num = "10";
let numInt = parseInt(num);
console.log(numInt); // 10
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let num = "10";
let numInt = Number(num);

console.log(numInt); // 10
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let num = "10";
let numInt = +num;

console.log(numInt); // 10
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String to Float

We can convert string float number to a float number. Any float number inside a quote is a string float number. An example of a string float number: '9.81', '3.14', '1.44', etc.
We can convert string float to number using the following methods:

  • parseFloat()
  • Number()
  • Plus sign(+)
let num = "9.81";
let numFloat = parseFloat(num);

console.log(numFloat); // 9.81
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let num = "9.81";
let numFloat = Number(num);

console.log(numFloat); // 9.81
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let num = "9.81";
let numFloat = +num;

console.log(numFloat); // 9.81
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Float to Int

We can convert float numbers to integers.
We use the following method to convert float to int:

  • parseInt()
let num = 9.81;
let numInt = parseInt(num);

console.log(numInt); // 9
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Now U Know About JavaScript Data Types And Its conversions 😎‴️

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