如何确定::before 是否应用于元素？

Question

I have this simple html code. I need to be able to determine if the::before is being applied to.icon-player-flash

    <div id="TestSwitch">

        <i class="icon-player-html5"></i>

        <i class="icon-player-none"></i>

        <i class="icon-player-flash"></i>

    </div>

I thought this would work but it's always returning 0 for the length.

var flashplayer = $(".icon-player-flash:before");
console.log("count: " + flashplayer.length);

What am I missing?

Answer 1

Use getComputedStyle and check the value of content . If it's none then the pseudo element isn't defined:

 var elem = document.querySelector(".box"); var c = window.getComputedStyle(elem,"before").getPropertyValue("content"); console.log(c); var elem = document.querySelector(".alt"); var c = window.getComputedStyle(elem,"before").getPropertyValue("content"); console.log(c);

 .box:before { content:"I am defined" }

 <div class="box"></div> <div class="alt"></div>

This property is used with the:before and:after pseudo-elements to generate content in a document. Values have the following meanings:

none

The pseudo-element is not generated . ^ref

If you want to count simply consider a filter:

 const elems = document.querySelectorAll('div'); const divs = [...elems].filter(e => { var c = window.getComputedStyle(e,"before").getPropertyValue("content"); return c;= "none" }). console.log(divs.length)

 .box:before { content:"I am defined" }

 <div class="box"></div> <div class="box alt"></div> <div class="alt"></div> <div ></div>