Is An Attribute Selector For The Id Attribute Less Specific Than An Id Selector?

What do I need to do to give the [id^=value] selector the same specificity as a regular ID, and why isn't it equal or greater already? (considering that I gave it html as well) htm

Solution 1:

An attribute selector will always be less specific than an ID selector; its specificity value does not change based on the attribute name. Selectors only maps specific attribute names to class selectors and ID selectors; an attribute selector is a generic concept and does not contain any such mappings.

The only way for a complex selector to have ID specificity is if it contains one or more ID selectors. Implementation limits aside, it is theoretically not possible to override even a single ID selector with any number of attribute selectors or any other type of simple selector.

Here is how your two selectors compare:

/* 1 attribute, 2 types -> specificity = 0-1-2 */htmldiv[id^="blue"] {
    background-color: blue
}

/* 1 ID                 -> specificity = 1-0-0 */#blue4 {
    background-color: red
}

Even the addition of html doesn't help because it's just a type selector. Change it to :root and you get a pseudo-class which is equally specific to an attribute selector, and thus still less specific than an ID.

Solution 2:

You may consider the not() selector in order to append a random ID and you will then have a higher or the same specifity since the specifity of not() is equal to the specifity of the selector inside it:

htmlbodydiv[id^="blue"]:not(#randomID) {
  background-color: blue
}

#blue4 {
  background-color: red
}

div {
  height: 50px;
  width: 50px
}

<divid="blue1"></div><divid="blue2"></div><divid="blue3"></div><divid="blue4"></div>