The fundamental part of most classes is its constructor, which sets up each instance's initial state and handles any parameters that were passed when calling new
.
It's defined in a class
block as though you're defining a method named constructor
, though it's actually handled as a special case.
class MyClass {
constructor(option) {
console.log(`Creating instance using ${option} option.`);
this.option = option;
}
}
Example usage:
const foo = new MyClass('speedy'); // logs: "Creating instance using speedy option"
A small thing to note is that a class constructor cannot be made static via the static
keyword, as described below for other methods.