angular.js - Questions about angular attribute directives

Question

@Directive({ selector: '[myHighlight]' })
The @Directive decorator requires a css selector in order to identify the HTML associated with this directive from the template

This is copied from the example on the official website. I have a question: Does the @Directive decorator need to find the myHighlight selector from all templates? If that's the case, isn't it very resource intensive? Generally speaking, shouldn’t you specify a template to look for?

某草草 · Answer

The document is very clear:

@Directive requires a CSS selector to identify the HTML in the
template that is associated with our directive. The CSS selector for
an attribute is the attribute name in square brackets. Our directive's
selector is [myHighlight]. Angular will locate all elements in the
template that have an attribute named myHighlight.

It should be to find all the elements that match this selector in the current template, which is very resource-consuming as you think. In fact, it is no different from jquery's selector.