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To remove any duplicates, we can pass our array into the new Set() constructor, then convert the returned collection back into an array.

Use Array.prototype.every() and Array.prototype.includes() to check if all elements of values are included in arr.

To check if the caps lock is on, you use the getModifierState() method of the KeyboardEvent object.

Use Array.prototype.some() and Array.prototype.includes() to check if at least one element of values is included in arr.

In some cases such as an inline editable element, or a messaging application, you would like to submit the data when user presses Enter. The only way to generate a new line is to press Shift and Enter.

Use Element.insertAdjacentHTML() with a position of ‘afterend’ to parse htmlString and insert it after the end of el.