Javascript to Swift

Free Javascript to Swift Code Converter

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Transform your code from Javascript to Swift with our free AI-based code convertion tool. If you like what you see, we also create documentation for your code! We don't ever store your code or any representation of it in our databases, but it will be shared with the LLM of our choice for processing.

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How to convert from Javascript to Swift

Converting code from JavaScript to Swift can seem daunting, especially for developers who are new to Swift. However, with an understanding of the fundamental differences and some practical examples, you can efficiently transition your code. This guide will help you transform your JavaScript code into Swift, providing a robust foundation for your projects.

Differences in Syntax and Paradigms

Syntax Overview

JavaScript and Swift have distinct syntaxes. Let's look at a quick example:

  • JavaScript:
    function greet(name) {
        console.log("Hello " + name);
  • Swift:
    func greet(name: String) {
        print("Hello \(name)")
    greet(name: "World")

As you can see, Swift uses func for function declarations, and string interpolation is done using \(variable) instead of concatenation.

Data Types and Variable Declarations

Variable Declaration

  • JavaScript:
    let age = 25; // or var age = 25; for mutable variable
  • Swift:
    var age = 25 // mutable variable
    let age = 25 // immutable variable

In Swift, let declares a constant, and var declares a variable. Type inference is strong in Swift, but types can be explicitly declared.

Type System

JavaScript is dynamically typed, while Swift is statically typed. Let's consider type assignment:

  • JavaScript:
    let name = "John Doe"; // string
    let age = 30; // number
  • Swift:
    let name: String = "John Doe"
    let age: Int = 30

Specifying types explicitly in Swift can prevent runtime errors, making your code safer and more predictable.

Functions and Methods

Function Declaration

  • JavaScript:
    function add(a, b) {
        return a + b;
  • Swift:
    func add(a: Int, b: Int) -> Int {
        return a + b

In Swift, you must specify the return type of the function and the types of its parameters.

Control Structures

Conditional Statements

  • JavaScript:
    if (age > 18) {
    } else {
  • Swift:
    if age > 18 {
    } else {

Swift uses more concise and readable syntax for control statements.

Arrays and Collections


  • JavaScript:
    let fruits = ["apple", "banana", "cherry"];
  • Swift:
    let fruits: [String] = ["apple", "banana", "cherry"]

Swift arrays require type declarations, making sure all elements are of the same type.

Accessing Elements

  • JavaScript:
    let firstFruit = fruits[0];
  • Swift:
    let firstFruit = fruits[0]

The syntax for accessing elements is similar, but Swift enforces type safety.


For Loops

  • JavaScript:
    for (let i = 0; i < 5; i++) {
  • Swift:
    for i in 0..<5 {

Swift provides a more expressive range-based for-loop.

Objects and Structs


  • JavaScript:
    let person = {
        name: "John",
        age: 25
  • Swift:
    struct Person {
        var name: String
        var age: Int
    let person = Person(name: "John", age: 25)

Swift uses structs and classes instead of JavaScript's objects for creating complex data types.

Advanced Topics

Closures and Arrow Functions

  • JavaScript:
    let greet = (name) => console.log("Hello " + name);
  • Swift:
    let greet: (String) -> Void = { name in
        print("Hello \(name)")

Closures in Swift are powerful but take a bit more syntax compared to JavaScript's arrow functions.


Converting from JavaScript to Swift involves understanding the key differences in syntax, data types, and language paradigms. While JavaScript is dynamic and flexible, Swift emphasizes type safety and performance. By grasping these distinctions and applying the examples provided, you can successfully convert your JavaScript code to Swift, leveraging the strengths of both languages.

Understanding these essentials will make your transition smoother, allowing you to create robust applications in Swift. Happy coding!

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