认识层次选择器

<div   class="ex">
    <span>3</span>
    <span class="sp1">1</span>
    <span>22222222222</span>
    <span>3</span>
    <span>3</span>
    <span>3</span>
    <span>3</span>
    <div class="subEx">
        <span>4</span>
        <span>5</span>
    </div>
</div>

<script>
    var num=$(".ex span").length;
    var num1=$(".ex>span").length;
    var txt1=$(".sp1+ span").text();
    var arr=$(".sp1~span")
    console.log(num);
    console.log(num1);
    console.log(txt1);
    console.log(arr.length);
</script>