Laravel - 即使代码在控制台中运行，Javascript CSS样式也不会得到应用

Question

来自highlight.js的

：

$(document).ready(function() 
{ 
    $("#myTable").tablesorter(); 
    setAllDifferentHeight();
    highlight();
} 
); 

function highlight()
{

    var firsts = document.getElementsByClassName("first");
    for(var i=0; i<firsts.length; i++){
        firsts[i].style.backgroundColor = "gold";
    }
    var seconds = document.getElementsByClassName("second");
    for(var i=0; i<seconds.length; i++){
        seconds[i].style.backgroundColor = "silver";
    }
    var thirds = document.getElementsByClassName("third");
    for(var i=0; i<thirds.length; i++){
        thirds[i].style.backgroundColor = "brown";
    }
    var lasts = document.getElementsByClassName("last");
    for (var i = lasts.length - 1; i >= 0; i--) {
        lasts[i].style.backgroundColor = "pink";
    }

}

来自index.blade.php的

：

        @foreach($student as $s)
        <?php $sum = $s->mc+$s->tc+$s->hw+$s->bs+$s->ks+$s->ac; ?>

        @if($sum == $first)
        <tr class = "first">
        @elseif($sum == $second)
        <tr class = "second">                   
        @elseif($sum == $third)
        <tr class = "third">                    
        @elseif($sum == $last)
        <tr class = "last">                 
        @endif

HTML是在正确的位置使用正确的类生成的，但javascript不会突出显示。当我在控制台中运行Javascript代码时，它会执行我想要的操作。这是什么问题？