Angular property binding begin with colon should throw error

[Zuckjet]

Which @angular/* package(s) are the source of the bug?

compiler

Is this a regression?

No

Description

with this code, Angular will treat the button as disabled(xxxx is any random string)

<button :disabled="xxxx">Disabled Button</button>

First, is there any document that Angular support this code style begin with colon(:) for property binding ?
If not, I think it is better to throw error

Please provide a link to a minimal reproduction of the bug

No response

Please provide the exception or error you saw

No response

Please provide the environment you discovered this bug in (run ng version)

No response

Anything else?

No response

[Narasim0406]

In angular for property binding, you should use [] not the colon.Please see the documentation over here.

<button [disabled]="xxxx">Disabled Button

[Zuckjet]

I know I should use [], but I think this behavior is weird.

this code sample run in plain html will not disable button, but in angular it will. If angular doesn't support this syntax(begin with :), why not just throw compile error or keep the same behavior with plain html ?

[JoostK]

The colon is interpreted as XML namespace separator, where the namespace prefix is left empty. That is not valid according to the XML specification, but Angular's parser/compiler accepts it to mean the default namespace.