The StylePropertyMapReadOnly.forEach() method executes a provided function once for each element of StylePropertyMapReadOnly.

callbackFn

The function to execute for each element, taking three arguments:

currentValue

The value of the current element being processed.

index Optional

The index of the current element being processed.

array Optional

The StylePropertyMapReadOnly that forEach() is being called on.

thisArg Optional

Value to use as this (i.e., the reference Object) when executing callback.

None (undefined).

Here is an example of using forEach() on a retrieved Element.computedStyleMap().

// get a button element
const buttonEl = document.querySelector(".example");

// we can retrieve all computed styles with `computedStyleMap`
const allComputedStyles = buttonEl.computedStyleMap();

// forEach will allow us to run code over each prop/val pair
allComputedStyles.forEach((elem, index, arr) => {
  // code to run for each pair
});