Swift and JavaScript comparison snippets(2) — Basic Operators

Assignment Operator

Swift

let b = 10
var a = 5
a = b
// decomposed tuple with multiple values into multiple variables
let (x, y) = (1, 2)
print("x = \(x), y = \(y)") // x = 1, y = 2

JavaScript

let b = 10
var a = 5
a = b
// object matching with destructuring assignment
const {x, y} = {x:1, y:2}
console.log(`x = ${x}, y = ${y}`) // x = 1, y = 2
// or array matching with destructuring assignment
const [x, y] = [1, 2]
console.log(`x = ${x}, y = ${y}`) // x = 1, y = 2

Arithmetic Operators

• Addition (+)
• Subtraction (-)
• Multiplication (*)
• Division (/)

Swift

1 + 2       // equals 3
5 - 3       // equals 2
2 * 3       // equals 6
10.0 / 2.5  // equals 4.0
"hello, " + "world"  // equals "hello, world"

JavaScript

1 + 2       // equals 3
5 - 3       // equals 2
2 * 3       // equals 6
10.0 / 2.5  // equals 4
"hello, " + "world"  // equals "hello, world"

Remainder Operator

Swift

9 % 4    // equals 1
-9 % 4   // equals -1

JavaScript

9 % 4    // equals 1
-9 % 4   // equals -1

Unary Minus/Plus Operator

Swift

let three = 3
let minusThree = -three       // minusThree equals -3
let plusThree = -minusThree   // plusThree equals 3, or "minus minus three"
let minusSix = -6
let alsoMinusSix = +minusSix  // alsoMinusSix equals -6

JavaScript

const three = 3
const minusThree = -three       // minusThree equals -3
const plusThree = -minusThree   // plusThree equals 3, or "minus minus three"
const minusSix = -6
const alsoMinusSix = +minusSix  // alsoMinusSix equals -6

Compound Assignment Operators

Swift

var a = 1
a += 2 // a is now equal to 3

JavaScript

let a = 1
a += 2 // a is now equal to 3

Comparison Operators

• Equal to (a == b)
• Not equal to (a != b)
• Greater than (a > b)
• Less than (a < b)
• Greater than or equal to (a >= b)
• Less than or equal to (a <= b)
• Identity operators, refer to the same object instance (a === b)
• Identity operators, not refer to the same object instance (a !== b)

Swift

1 == 1   // true because 1 is equal to 1
2 != 1   // true because 2 is not equal to 1
2 > 1    // true because 2 is greater than 1
1 < 2    // true because 1 is less than 2
1 >= 1   // true because 1 is greater than or equal to 1
2 <= 1   // false because 2 is not less than or equal to 1
let name = "world"
if name == "world" {
    print("hello, world")
} else {
    print("I'm sorry \(name), but I don't recognize you")
}
// Prints "hello, world", because name is indeed equal to "world".
let p1 = Person();
let p2 = Person();
p1 === p2 // false
p1 !== p2 // true

JavaScript

1 == 1   // true because 1 is equal to 1
2 != 1   // true because 2 is not equal to 1
2 > 1    // true because 2 is greater than 1
1 < 2    // true because 1 is less than 2
1 >= 1   // true because 1 is greater than or equal to 1
2 <= 1   // false because 2 is not less than or equal to 1
const name = "world"
if (name == "world") {
    console.log("hello, world")
} else {
    console.log(`I'm sorry ${name}, but I don't recognize you`)
}
// Prints "hello, world", because name is indeed equal to "world".
const p1 = new Person();
const p2 = new Person();
p1 === p2 // false
p1 !== p2 // true

Ternary Conditional Operator

Swift

let contentHeight = 40
let hasHeader = true
let rowHeight = contentHeight + (hasHeader ? 50 : 20)
// rowHeight is equal to 90

JavaScript

const contentHeight = 40
const hasHeader = true
const rowHeight = contentHeight + (hasHeader ? 50 : 20)
// rowHeight is equal to 90

Logical Operators

• Logical NOT (!a)
• Logical AND (a && b)
• Logical OR (a || b)

Swift

let allowedEntry = false
if !allowedEntry {
    print("ACCESS DENIED")
}
// Prints "ACCESS DENIED"

let hasDoorKey = false
let knowsOverridePassword = true
if enteredDoorCode && passedRetinaScan || hasDoorKey || knowsOverridePassword {
    print("Welcome!")
} else {
    print("ACCESS DENIED")
}
// Prints "Welcome!"

JavaScript

const allowedEntry = false
if (!allowedEntry) {
    console.log("ACCESS DENIED")
}
// Prints "ACCESS DENIED"

const hasDoorKey = false
const knowsOverridePassword = true
if (enteredDoorCode && passedRetinaScan || hasDoorKey || knowsOverridePassword) {
    console.log("Welcome!")
} else {
    console.log("ACCESS DENIED")
}
// Prints "Welcome!"

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