You're right, these are not directives.
Angular compiler creates a view factory for each component with view nodes. For each view node the compiler defines a set of bindings types using the bitmask. There are different binding types and hence different types of operations performed during change detection to reflect changes in the component class.
You probably know about the standard input mechanism that allows updating the property:
<div [prop]="myAriaRole">
The compiler creates the TypeProperty
binding for it:
TypeProperty = 1 << 3
and hence the operation to update the element property is used during change detection.
The special syntax attr.*
, class.*
and style.*
defines different type of bindings:
TypeElementAttribute = 1 << 0,
TypeElementClass = 1 << 1,
TypeElementStyle = 1 << 2,
so during change detection for each type of binding corresponding operation is used:
function CheckAndUpdateElement() {
...
case BindingFlags.TypeElementAttribute -> setElementAttribute
case BindingFlags.TypeElementClass -> setElementClass
case BindingFlags.TypeElementStyle -> setElementStyle
case BindingFlags.TypeProperty -> setElementProperty;
To learn about Angular internals related to view and bindings I strongly recommend reading:
Since all bindings are processed during change detection also read:
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