JavaScript - StackHowTo

How to check if a variable exists or is defined in JavaScript

In some cases, your JavaScript code may need to depend on a particular variable. If you want to check if

Undefined variable. This is an error message that indicates that a variable inside a JavaScript code is declared but has

To trigger or pause a CSS animation in Javascript. You can use the animationPlayState property of the HTML DOM style

To increase and decrease image size. You can use JavaScript’s width or height property to proportionally increase or decrease the

You can simply use JavaScript’s width and height properties to change the size of your image, as shown in the

You can use JavaScript’s clientWidth and clientHeight properties to get the current width and height of an image. These properties

You can easily create a string by concatenating the elements of an array using JavaScript’s join() method. The join() method

The following example will show you how to define a function in JavaScript. In the following code, when the button

You can use the splice() method to remove elements from an array at any index. The syntax for removing an

You can use the forEach() method in combination with the Object.keys() method to remove duplicate values from an array or