TypeError: Assignment to read-only properties is not allowed in strict mode

By a show of hands, how many knew that HTMLElement.style is readonly?

Styles should not be set by assigning a string directly to the style property (as in element.style = "color: blue;"), since it is considered read-only, as the style attribute returns a CSSStyleDeclaration object which is also read-only.

Anyway, element.style = "color: blue;" will give you the following error in strict mode:

TypeError: Assignment to read-only properties is not allowed in strict mode