Category: JavaScript Answers

Sometimes, we want to call class constructor without new keyword with JavaScript.

In this article, we’ll look at how to call class constructor without new keyword with JavaScript.

How to call class constructor without new keyword with JavaScript?

To call class constructor without new keyword with JavaScript, we can define an arrow function and call it.

For instance, we write

const Foo = (x) => ({
  x,
  hello: () => `hello ${x}`,
  increment: () => Foo(x + 1),
  add: ({ x: y }) => Foo(x + y),
});

console.log(Foo(1).x);
console.log(Foo(1).hello());

to define the Foo arrow function that returns an object with the properties we want.

Then we call Foo to return a new object and access properties from it.

Conclusion

To call class constructor without new keyword with JavaScript, we can define an arrow function and call it.

Sometimes, we want to disable arrow key scrolling in users browser with JavaScript.

In this article, we’ll look at how to disable arrow key scrolling in users browser with JavaScript.

How to disable arrow key scrolling in users browser with JavaScript?

To disable arrow key scrolling in users browser with JavaScript, we disable the default behavior for arrow keys and the space key.

For instance, we write

window.addEventListener(
  "keydown",
  (e) => {
    if (
      ["Space", "ArrowUp", "ArrowDown", "ArrowLeft", "ArrowRight"].includes(
        e.code
      )
    ) {
      e.preventDefault();
    }
  },
  false
);

to call window.addEventListener to listen to the keydown event.

In the keydown event listener, we check if e.code is one of "Space", "ArrowUp", "ArrowDown", "ArrowLeft", or "ArrowRight".

If it is, then we call e.preventDefault to stop the default behavior.

Conclusion

To disable arrow key scrolling in users browser with JavaScript, we disable the default behavior for arrow keys and the space key.

Sometimes, we want to fix CKEditor instance already exists error with JavaScript.

In this article, we’ll look at how to fix CKEditor instance already exists error with JavaScript.

How to fix CKEditor instance already exists error with JavaScript?

To fix CKEditor instance already exists error with JavaScript, we destroy the existing instance if it already exists.

For instance, we write

const editor = CKEDITOR.instances[name];
if (editor) {
  editor.destroy(true);
}
CKEDITOR.replace(name);

to get the editor instance with CKEDITOR.instances[name].

If editor is defined, then we call editor.destroy with true to destroy the instance.

Then we call CKEDITOR.replace with name to create a new CKEditor instance with name.

Conclusion

To fix CKEditor instance already exists error with JavaScript, we destroy the existing instance if it already exists.

Sometimes, we want to test if value is a function with JavaScript.

In this article, we’ll look at how to test if value is a function with JavaScript.

How to test if value is a function with JavaScript?

To test if value is a function with JavaScript, we can use the typeof operator.

For instance, we write

typeof document.getElementById("myform").onsubmit === "function";

to check if the document.getElementById("myform").onsubmit property is a function by checking if typeof document.getElementById("myform").onsubmit returns 'function'.

If it does, then it’s a function.

Conclusion

To test if value is a function with JavaScript, we can use the typeof operator.

Sometimes, we want to check if a variable is a Date in JavaScript.

In this article, we’ll look at how to check if a variable is a Date in JavaScript.

How to check if a variable is a Date in JavaScript?

To check if a variable is a Date in JavaScript, we can use the instanceof operator.

For instance, we write

myVar instanceof Date;

to check if myVar is a Date instance with the instanceof operator to check if it’s a date.

Conclusion

To check if a variable is a Date in JavaScript, we can use the instanceof operator.