javascript - I am a little confused, why can I directly use checked=true to add effects to tags in js?

Question

For example: I need to use js to add a selected effect to the button.

Why can you directly use op.checked = true? to add the selected effect in js? Why don't you need to add a style in the middle? If it is color, it is like this op.style.color = "red" ?

Answer 1

Add css attributes after style. checked is an attribute of input, so there is no need to add style.

Answer 2

In fact, it’s the same if you write it directly in the html tag,

<input type="checkbox" checked/>
<span style="color:red"></span>

You write directly

<span color="red"></span>

It must be ineffective, one is the attribute of tag and the other is style