Could you clarify the significance of the brackets in this TypeScript Lambda Expression?

Question

Could you clarify the significance of the brackets in this TypeScript Lambda Expression?

I'm currently delving into an Angular book, but I'm struggling to locate any definitive documentation regarding the usage of square brackets in a lambda expression like

[hours, rate]) => this.total = hours * rate

. While I grasp that these parameters (hours and rate) can be accessed within the lambda function's body, I am puzzled by why

(hours, rate) => this.total = hours * rate)

is not functioning as expected and why the brackets [] are necessary.

Observable.combineLatest(this.invoiceForm.get('hours').valueChanges,
this.invoiceForm.get('rate').valueChanges).subscribe(
  ([hours, rate]) => this.total = hours * rate);

If anyone could shed some light on what this syntax signifies and direct me towards relevant documentation, it would be greatly appreciated.

Just a heads up: I have a good grasp on what combineLatest accomplishes; my confusion lies specifically with the lambda expression using those brackets.

javascript typescript lambda ecmascript-6

Answer 1

Answer №1

Think of it in terms of a destructuring assignment:

function example([x, y]) {
  console.log(x, ',', y)

}

example([5, 10])

In this code snippet, the parameters [x, y] represent the array being passed into the function. The first element of the array will be assigned to variable x, and the second element to variable y.

Answer 2

Think of it in terms of a destructuring assignment:

function example([x, y]) {
  console.log(x, ',', y)

}

example([5, 10])

In this code snippet, the parameters [x, y] represent the array being passed into the function. The first element of the array will be assigned to variable x, and the second element to variable y.

Answer 3

Answer №2

Understanding the combineLatest operator in Rx:

This operator will emit the most recent values from each observable whenever any of them emits a value.

Find out more about combineLatest here

Answer 4

Understanding the combineLatest operator in Rx:

This operator will emit the most recent values from each observable whenever any of them emits a value.

Find out more about combineLatest here

Could you clarify the significance of the brackets in this TypeScript Lambda Expression?

Answer №1

Answer №2

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