Can You Call a Class Constructor Without \'new\' in ES6?
Oct 26, 2024 am 01:55 AMCall Class Constructor Without new Keyword in ES6
Given the class definition:
class Foo { constructor(x) { if (!(this instanceof Foo)) return new Foo(x); this.x = x; } hello() { return `hello ${this.x}`; } }
It is not possible to directly call the class constructor without the new keyword. This is because classes in ES6 inherently have a constructor function that is invoked when the class is called.
Invoking a class without new results in an error:
Cannot call a class as a function
This error message clearly indicates that the class constructor can only be called with the new operator, which is required to create a new instance of the class.
To overcome this limitation, consider the following approaches:
- Use a regular function instead:
function Foo(x) { this.x = x; this.hello = function() { return `hello ${this.x}`; } }
- Always call the class with new:
(new Foo("world")).hello(); // "hello world"
- Wrap the class in a function and call with new:
var FooWrapper = function(...args) { return new Foo(...args) }; FooWrapper("world").hello(); // "hello world"
The above is the detailed content of Can You Call a Class Constructor Without \'new\' in ES6?. For more information, please follow other related articles on the PHP Chinese website!

Hot Article

Hot tools Tags

Hot Article

Hot Article Tags

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

Replace String Characters in JavaScript

HTTP Debugging with Node and http-console

Custom Google Search API Setup Tutorial
