Dart vs. JavaScript
Just a few examples to show you'll feel familiar - but you'll also have to learn new rules
Below, you'll find a completely incomplete list 🤪, but it is intended to show that there are many similarities between Dart and JavaScript, making it easier to switch between the two languages or even learn both simultaneously. There are other rules too, but you can easily learn them.
Some more comprehensive information you can find in the official docs. Here are two links:
👉 Learning Dart as a JavaScript developer
Variable declaration
Like in JavaScript, in Dart var is short for variable. It is used to declare a variable whose type is statically inferred:
var mystr = "shimmer";
In the example above, we declare a variable of type String. One of the convenient features of Dart is that it's able to infer the type of a variable based on the value that's assigned to it. Here, it's quite evident that it's a String type.
But unlike JavaScript, you CANNOT change the type of the variable afterwards!
var mystr = "shimmer";
mystr = 10; // THIS ASSIGNMENT DOESN'T WORK!
When we attempt to change the type of a variable in Dart, the compiler will generate an error. This is because Dart is a statically typed language, which means that the data type of a variable is determined at compile-time and cannot be changed during runtime.
Another way to declare variables is the explicit type declaration:
String mystr = "shimmer";
In Dart, it's generally considered good practice to explicitly declare the data type of a property when defining a class. This helps to ensure that the code is more easily understood and maintainable, especially when working on larger projects with multiple developers.
For variables within smaller scopes, such as a method, the "var" keyword can be used instead of explicitly declaring the data type. This is because the scope is smaller and it's often easier to infer the type of the variable based on the context of the code.
class MyCat {
String cat = "Bob";
void someMethod() {
var anotherVariable = "Tom";
}
}
Defining a function
JavaScript
function addNumbers(a, b) {
return a + b;
}
Dart
int addNumbers(int a, int b) {
return a + b;
}
Working with arrays
JavaScript
var fruits = ["apple", "strawberry", "cherry"];
fruits.push("kiwi");
Dart
List<String> fruits = ['apple', 'strawberry', 'cherry'];
fruits.add('kiwi');
Using dot notation to access object properties and methods
JavaScript
class Person {
constructor() {
this.name = "";
this.age = 0;
}
greet() {
console.log(
`Hello, my name is ${this.name} and I'm ${this.age} years old.`
);
}
}
var person = new Person();
person.name = "Joe";
person.age = 44;
person.greet();
Dart
class Person {
String name;
int age;
void greet() {
print("Hello, my name is $name and I'm $age years old.");
}
}
var person = Person();
person.name = "Joe";
person.age = 44;
person.greet();
Usage of string interpolation
JavaScript
var name = "Joe";
console.log(`Hello, my name is ${name}`);
Dart
var name = "Joe";
print("Hello, my name is $name");
Usage of operators
JavaScript
var x = 10;
var y = 5;
var z = x + y;
Dart
var x = 10;
var y = 5;
var z = x + y;
Usage of if statements
JavaScript
var age = 25;
if (age >= 18) {
console.log("You are an adult");
} else {
console.log("You are a minor");
}
Dart
var age = 25;
if (age >= 18) {
print("You are an adult");
} else {
print("You are a minor");
}
Usage of switch statements
JavaScript
var fruit = "apple";
switch (fruit) {
case "banana":
console.log("This is a banana");
break;
case "apple":
console.log("This is an apple");
break;
default:
console.log("This is not a fruit");
}
Dart
var fruit = "apple";
switch (fruit) {
case "banana":
print("This is a banana");
break;
case "apple":
print("This is an apple");
break;
default:
print("This is not a fruit");
}
Usage of try-catch blocks
JavaScript
try {
// code that may throw an error
} catch (error) {
console.log(`Error: ${error.message}`);
}
Dart
try {
// code that may throw an error
} catch (error) {
print("Error: ${error.toString()}");
}